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Susitna-Watana Hydroelectric Project Document
ARLIS Uniform Cover Page
Title:
SuWa 230
Ice processes in the Susitna River study (Study 7.6), detailed ice
observations, October 2013 - May 2014, technical memorandum
Author(s) – Personal:
Author(s) – Corporate:
HDR Alaska, Inc.
AEA-identified category, if specified:
September 17, 2014 technical memorandum filings
AEA-identified series, if specified:
Series (ARLIS-assigned report number): Existing numbers on document:
Susitna-Watana Hydroelectric Project document number 230
Published by: Date published:
[Anchorage, Alaska : Alaska Energy Authority, 2014] September 2014
Published for: Date or date range of report: Prepared for Alaska Energy Authority
Volume and/or Part numbers:
Final or Draft status, as indicated:
Attachment B
Document type: Pagination:
Technical memorandum vi, 42, 14, 9 p.
Related work(s): Pages added/changed by ARLIS:
Cover letter to this report: Susitna-Watana Hydroelectric
Project, FERC Project no. 14241-000; Initial filing of September
2014 technical memoranda. (SuWa 228)
Attachments A and C-J (SuWa 229 and 231-238)
Added cover letter
Notes:
All reports in the Susitna-Watana Hydroelectric Project Document series include an ARLIS-
produced cover page and an ARLIS-assigned number for uniformity and citability. All reports
are posted online at http://www.arlis.org/resources/susitna-watana/
September 17, 2014
Ms. Kimberly D. Bose
Secretary
Federal Energy Regulatory Commission
888 First Street, N.E.
Washington, D.C. 20426
Re:Susitna-Watana Hydroelectric Project, Project No. 14241-000
Initial Filing of September 2014 Technical Memoranda
Dear Secretary Bose:
By letter dated January 28, 2014, the Federal Energy Regulatory Commission
(Commission or FERC) extended the procedural schedule for the preparation and review
of the Initial Study Report (ISR) for the proposed Susitna-Watana Hydroelectric Project,
FERC Project No. 14241 (Project).1 In particular, the Commission’s January 28 letter
established a deadline of June 3, 2014 for the Alaska Energy Authority (AEA) to file the
ISR, and provided a 120-day period for licensing participants to review the ISR prior to
the ISR meetings, which are scheduled to begin the week of October 13.2 The purpose of
this filing is to provide several technical memoranda to Commission Staff and licensing
participants prior to the ISR meetings.
As required by the Commission’s January 28 letter, AEA filed the ISR with the
Commission on June 3. Among other things, the ISR detailed AEA’s planned work
during the 2014 field season.3 As AEA was preparing this 2014 work plan, it recognized
that data gathered during the 2014 field season, together with other study work conducted
prior to the October 2014 ISR meetings,could assist Commission Staff, AEA, and other
licensing participants in developing the Project’s licensing study program for 2015. For
this reason, the ISR provided for AEA to prepare certain technical memoranda and other
information based on 2014 work.
AEA recognizes that Commission Staff and licensing participants need a
reasonable amount of time prior to the ISR meetings to review this additional
information. AEA and licensing participants consulted with Commission Staff on this
1 Letter from Jeff Wright, Federal Energy Regulatory Commission, to Wayne Dyok, Alaska Energy
Authority, Project No. 14241-000 (issued Jan. 28, 2014)[hereinafter, “January 28 letter”].
2 The full schedule for the ISR meetings appears in Section 1.5 of the ISR, as well as on AEA’s
licensing website, http://www.susitna-watanahydro.org/meetings/.
3 E.g., Initial Study Report §1.3 & Table 3, Project No. 14241-000 (filed June 3, 2014) [hereinafter,
“ISR”].
2
matter, and Staff directed that any additional information should be filed with the
Commission and made available to licensing participants no later than 15 days prior to
the ISR meetings, consistent with the typically applicable deadline under the
Commission’s Integrated Licensing Process regulations.4
With this letter, AEA is filing and distributing the first set of technical
memoranda and other information generated during the 2014 study season, as described
below. As part of its continued implementation of the study plan, AEA expects to file
certain additional technical memoranda prior to October 1, 2014, in accordance with
Commission Staff direction.
This first set of technical memoranda and other information consists of the
following:
Attachment A: Proposal to Eliminate the Chulitna Corridor from Further
Study. As explained in the ISR, throughout the licensing process AEA has
continually evaluated its proposal for Project development based on
environmental review, technical feasibility, practical considerations, and other
factors. As part of this iterative process, AEA notified the Commission and
licensing participants in the ISR that it was evaluating whether to continue
study of the Chulitna Corridor.5 Attachment A details AEA’s conclusion that
development of the Chulitna Corridor is not a reasonable alternative, and
therefore AEA proposes to eliminate the corridor from further study. AEA
seeks any comments or information on this proposal from federal and state
resource agencies and other participants in the licensing process.
Attachment B: Ice Processes in the Susitna River Study (Study 7.6),Detailed
Ice Observations October 2013 –May 2014 Technical Memorandum. The
ISR indicated that AEA would provide a summary of the 2014 break-up
observations.6 This technical memorandum describes all field activities and
observations between October 16, 2013 and May 15, 2014 for the Ice
Processes in the Susitna River Study (Study 7.6).
Attachment C: Study of Fish Distribution and Abundance in the Upper
Susitna River (Study 9.5), Proposed 2015 Modifications to Fish Distribution
and Abundance Study Plan Implementation Technical Memorandum. Based
on AEA’s experience in implementing the study plan for the Study of Fish
Distribution and Abundance in the Upper Susitna River (Study 9.5)during
2014, this technical memorandum proposes to continue certain modifications
to the implementation of this study during 2015.
4 See 18 C.F.R. §5.15(c)(2).
5 See ISR, ISR Overview §1.4.
6 See id., Ice Processes in the Susitna River Study,Study Plan 7.6, Part C §7.2.
3
Attachment D: Study of Fish Distribution and Abundance in the Middle and
Lower Susitna River Study (Study 9.6), 2013-2014 Winter Fish Study
Technical Memorandum. At the time the ISR was filed, AEA was still in the
process of conducting data entry, quality control, and analysis of winter
sampling for this study. AEA reported in the ISR that it would develop plans
for completing this study in a technical memorandum to be filed with the
Commission.7 This technical memorandum fulfills this commitment and sets
forth AEA’s proposal for winter efforts, including proposed methodologies
and modifications.
Attachment E: Characterization and Mapping of Aquatic Habitats (Study
9.9), 2013 and 2014 Aquatic Habitat Mapping Field Season Completion
Progress Technical Memorandum. In the ISR, AEA reported that its 2014
activities for the Characterization and Mapping of Aquatic Habitats Study
(Study 9.9) would consist of various ground-truthing surveys and collection of
habitat information for the 12 lakes within the potential reservoir inundation
zone.8 This technical memorandum reports on these activities.
Attachment F: Eulachon Run Timing, Distribution, and Spawning in the
Susitna River (Study 9.16), 2015 Proposed Eulachon Spawning Habitat Study
Modifications Technical Memorandum.After reviewing the 2013 and 2014
results from the Cook Inlet Beluga Whale Study (Study 9.17) and discussing
the results with the National Marine Fisheries Service, AEA has determined
that additional data are needed regarding eulachon spawning habitats. This
technical memorandum describes a proposed modification to the Study of
Eulachon Run Timing, Distribution and Spawning in the Susitna River (Study
9.16)to include an assessment of eulachon spawning habitats.
Attachment G: Fish and Aquatics Instream Flow Study (Study 8.5),
Evaluation of Relationships between Fish Abundance and Specific
Microhabitat Variables Technical Memorandum. Consistent with the
Commission’s study plan determination,9 this technical memorandum
provides a detailed evaluation of the comparison of fish abundance measures
with specific microhabitat variable measurements where sampling overlaps.
This memorandum is used to determine whether a relationship between a
specific microhabitat variable and fish abundance is evident.
Attachment H: Fish and Aquatics Instream Flow Study (Study 8.5), 2013-
2014 Instream Flow Winter Studies Technical Memorandum.In the ISR,
AEA reported that it would distribute its finding concerning the 2013-2014
7 See id., Study of Fish Distribution and Abundance in the Middle and Lower Susitna River Study,
Study Plan 9.6, Part C §7.1.2.5.
8 See id., Characterization and Mapping of Aquatic Habitats, Study Plan 9.9, Part C § 7.1.
9 See Study Plan Determination on 14 Remaining Studies for the Susitna-Watana Hydroelectric Project,
Appendix B at B-84 to B-86, Project No. 14241-000 (issued Apr. 1, 2013).
4
winter activities in 2014.10 This technical memorandum describes the
methods applied, and data and information collected, as part of the Instream
Flow Study 2013-2014 winter studies.
Attachment I: Geomorphology Study (Study 6.5), Susitna River Historical
Cross Section Comparison (1980s to Current) Technical Memorandum. As
specified in Revised Study Plan Section 6.5.4.1.2.3, this technical
memorandum describes changes within the main and side channels of the
Susitna River by comparing historical survey data from the 1980s with survey
data from the current Project.
Attachment J: Geomorphology Study (Study 6.5), 2014 Update of Sediment-
Transport Relationships and a Revised Sediment Balance for the Middle and
Lower Susitna River Segments Technical Memorandum. The purpose of this
technical memorandum is to update the sediment load rating curves and
preliminary estimates of the overall sediment balance in the Middle and
Lower River segments under pre-Project conditions that were initially
provided in “Development of Sediment-Transport Relationships and an Initial
Sediment Balance for the Middle and Lower Susitna River Segments,” (Tetra
Tech, Inc. 2013a). This update is based on additional data collected by the
U.S. Geological Survey in 2012 and 2013.
AEA appreciates the opportunity to provide this additional information to the
Commission and licensing participants, which it believes will be helpful in determining
the appropriate development of the 2015 study plan as set forth in the ISR. If you have
questions concerning this submission please contact me at wdyok@aidea.org or (907)
771-3955.
Sincerely,
Wayne Dyok
Project Manager
Alaska Energy Authority
Attachments
cc: Distribution List (w/o Attachments)
10 See ISR, Fish and Aquatics Instream Flow Study, Study Plan 8.5, Part C §7.5.2.
Susitna-Watana Hydroelectric Project
(FERC No. 14241)
Ice Processes in the Susitna River Study
(Study 7.6)
Detailed Ice Observations
October 2013 – May 2014
Technical Memorandum
Prepared for
Alaska Energy Authority
Prepared by
HDR Alaska, Inc.
September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
TABLE OF CONTENTS
Abstract ......................................................................................................................................... vi
1. Introduction ............................................................................................................................ 1
2. Study Objectives .................................................................................................................... 1
3. Study Area .............................................................................................................................. 2
4. Methods .................................................................................................................................. 3
4.1. Aerial Reconnaissance ................................................................................................... 3
4.2. Time-Lapse Camera Monitoring .................................................................................... 4
4.3. Meteorological Data Collection ..................................................................................... 4
5. Results ..................................................................................................................................... 5
5.1. Freeze-up Observations .................................................................................................. 5
5.1.1. Lower River Observations ...................................................................................... 6
5.1.2. Middle River Observations ..................................................................................... 8
5.1.3. Upper River Observations..................................................................................... 11
5.2. Open Lead Mapping ..................................................................................................... 12
5.2.1. Lower River .......................................................................................................... 13
5.2.2. Middle River ......................................................................................................... 13
5.2.3. Upper River ........................................................................................................... 14
5.3. Breakup Observations .................................................................................................. 14
5.3.1. Lower River Observations .................................................................................... 15
5.3.2. Middle River Observations ................................................................................... 18
5.3.3. Upper River Observations..................................................................................... 23
5.4. Meteorological Data Collection ................................................................................... 25
6. Literature Cited ................................................................................................................... 25
7. Tables .................................................................................................................................... 27
8. Figures .................................................................................................................................. 28
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page ii September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
LIST OF TABLES
Table 4.1-1. Time-Lapse Camera Information ............................................................................. 27
LIST OF FIGURES
Figure 3.1 - 1.Map of Ice Processes Study Area ............................................................................28
Figure 4.2 - 1. Map of Time-Lapse Camera Locations and Pressure Transducers ........................29
Figure 5.1 - 1. Susitna River at Tsusena Creek USGS Gage, #152917000. Note: 2012 Discharge
was Maximum discharge for period of record ...............................................................................30
Figure 5.1 - 2. Susitna River at Gold Creek USGS Gage, #15292400 ..........................................30
Figure 5.1 - 3. Susitna River at Sunshine USGS Gage, # 15292480 .............................................31
Figure 5.1 - 4. Average Monthly Temperatures at Talkeetna ........................................................31
Figure 5.1 - 5. Ice Front Progression and Ice Bridge Locations – Freeze-up 2012 .......................32
Figure 5.1 - 6. Ice Front Progression and Ice Bridge Locations – Freeze-up 2013 .......................33
Figure 5.1 - 7. Ice bridge formed near the mouth of the Susitna river on November 12, 2013 ....34
Figure 5.1 - 8. Frazil ice moving through the Delta Islands area ...................................................34
Figure 5.1 - 9.Heavy frazil and border ice growth on Middle River on Novermber 8, 2013 ........35
Figure 5.1 - 10. Anchor ice deposits on the bed on December 3, 2013 .........................................35
Figure 5.1 - 11. Shear walls and frazil jams in Devils Canyon on December 18, 2013 ................36
Figure 5.1 - 12. Anchor ice and border ice growth on the Upper River on November 19, 2013 ..36
Figure 5.2 - 1. Open velocity lead follwoign thalweg in Lower River on February 21, 2014 ......37
Figure 5.2 - 2. Open thermal lead following edge of island on February 21, 2014 .......................37
Figure 5.2 - 3. Thermal lead along right bank at FA-104 on February 21, 2014 ...........................38
Figure 5.2 - 4. Open velocity lead in the Upper River on February 20, 2014 ...............................38
Figure 5.3 - 1. Downstream edge of ice cover in Lower River on April 28, 2014 ....................... 39
Figure 5.3 - 2. Mouth of the Talkeetna river on April 28, 2014 ................................................... 39
Figure 5.3 - 3. FA-128 showing Slough 8A open on April 25, 2014 ........................................... 40
Figure 5.3 - 4. Ice jam and overbank flooding upstream of FA-128 on May 5, 2014 .................. 40
Figure 5.3 - 5. Shear walls upstream of FA-104 on May 8, 2014 ................................................ 41
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page iii September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Figure 5.3 - 6. Flooded ice surface at thalweg, Upper River on April 23, 2014 ........................... 41
Figure 5.3 - 7. Evidence of previous jam at mouth of the Oshetna River on May 2, 2014 .......... 42
APPENDICES
Appendix A: Meteorological Data for the Susitna Basin
Appendix B: Susitna River Surface Water Station Data
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page iv September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
LIST OF ACRONYMS, ABBREVIATIONS, AND DEFINITIONS
Abbreviation Definition
AEA Alaska Energy Authority
ESS Alaska Energy Authority station on the Susitna River for Surface water
FA Focus Area (Aquatic Habitat)
FERC Federal Energy Regulatory Commission
GIS Geographic Information System
HDR HDR, Inc.
HEC-RAS Hydrologic Engineering Centers River Analysis System
ILP Integrated Licensing Process
NEPA National Environmental Policy Act
NWS National Weather Service
PAD Pre-Application Document
PRM Project River Mile
Project Susitna-Watana Hydroelectric Project
SNOTEL National Water and Climate Center Snow Telemetry Data
USACE U.S. Army Corps of Engineers
USGS U.S. Geological Survey
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page v September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
ABSTRACT
This 2014 Spring Technical Memorandum describes all field activities and observations between
October 16, 2013 and May 15, 2014 for the Ice Processes in the Susitna River Study. In general,
freeze-up was characterized as being at or above long term averages for air temperatures during
winter. The ice front progressed upstream from the mouth following the formation of an ice
bridge at the mouth between November 8 and 12 and the front passed Talkeetna by November
25. Freeze-up progressed steadily through December 23 with dominant ice covers extending
from PRM 4 to 122, PRM 129 to 143, 147.5 to 152.3, and from 183.7 to 222.3. Continued cold
air temperatures extended these covers, allowing some to join together. Warm air temperatures
in January resulted in some melting and opening of leads but the return of cold in February
continued ice growth throughout the remainder of the winter and into spring. Open leads surveys
were flown twice in 2014. One survey was conducted on February 20th and 21st to characterize
the open leads at the mid-winter but prior to the low flows of the year. The lower and upper
river were split into two flights due to the restrictions of daylight in February. The second
survey was flown in the spring on April 2nd and represented the leads present at the end of
freezing conditions (near the minimum flows of the year) prior to thawing temperatures and
breakup. Leads were classified as thermal or velocity in origin and the location of each was
identified as main channel or off channel/slough. Breakup was characterized by mild
temperatures matching long term averages and less than normal snowpack. These factors
contributed to a generally thermal melt-out of the ice cover with few jams and flooding events.
Large jams occurred at FA-104 and FA-128 with ice pushed into overbank areas. However, a
majority of the river experienced gradual melting and deteriorating of ice in place and the ice
was flushed from most reachs of the main channel of the river between May 5 and 8.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page vi September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
1. INTRODUCTION
The Alaska Energy Authority (AEA) is preparing a License Application that will be submitted to
the Federal Energy Regulatory Commission (FERC) for the Susitna-Watana Hydroelectric
Project (Project) using the Integrated Licensing Process (ILP). The Project is located on the
Susitna River, an approximately 300-mile-long river in the Southcentral region of Alaska. The
Project’s dam site, Watana Dam, would be located at Project River Mile (PRM) 187.2.
Project construction and operation as described in the Pre-application Document (PAD) would
modify the flow and water temperature regimes of the Susitna River downstream of Watana
Dam. The Project also has the potential to affect ice processes downstream of the Watana Dam
site as the reservoir would remove the upstream source of ice from the downstream river reaches.
The current ice processes that occur in the river (e.g., freeze up and breakup) likely had an effect
on river geomorphology, fish and aquatic habitat, riparian vegetation, and potentially other
resources (e.g., wildlife). The results of this study provide information that will serve as the basis
for preparing Exhibit E of a license application (18 CFR 4.41) and for use in FERC’s National
Environmental Policy Act (NEPA) analysis for the Project license.
One of the objectives of the Ice Processes Study is to document ice cover conditions in the
Susitna River from Cook Inlet (PRM 0) to the Oshetna River confluence at PRM 235.2. This
report provides the results of the 2013/2014 Susitna River Ice Processes Study from October
2013 to May 2014. Field activities included aerial breakup and freeze up reconnaissance, mid-
and late winter open-lead mapping, and time-lapse camera installation, maintenance, and review.
Research activities included meteorological data compilation, time-lapse video creation, and data
management and entry in a Global Information System (GIS) database. The results from these
efforts will be used to characterize the Susitna River ice regime, identify spatial and temporal
variations in ice processes, and provide information on the physical channel environment in the
winter to other study disciplines. Some of the information (aerial reconnaissance) is similar to
information collected during previous year’s studies including work done in the 1980s.
Collecting observations in a similar manner over a period of years will help define the year-to-
year variability in the ice regime. Characterizing the existing ice regime and its variability due to
climatic conditions will provide a basis for evaluating the impacts of the Project.
2. STUDY OBJECTIVES
As stated in the Revised Study Plan (RSP), the Ice Processes in the Susitna River Study (Study
7.6) will further the understanding of natural ice processes in the Susitna River and provide a
method to model/predict pre-Project and post-Project ice processes in the Susitna River. The
study will provide a basis for impact assessment, which will inform the development of any
necessary protection, mitigation, and enhancement measures. The study also will provide ice
processes input data for other resource studies with winter components (e.g., Fluvial
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 1 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Geomorphology Modeling below Watana Dam Study [Study 6.6], Instream Flow Studies
[Studies 8.5-8.6], Instream Flow Riparian [ISR Study 8.6], and Groundwater Study [Study 7.5]).
2.1. Study Goals and Objectives
The overall goals of the Ice Processes in the Susitna River Study (Study 7.6) are to understand
existing ice processes in the Susitna River and to predict post-Project ice processes. The specific
objectives are as follows:
• Document the timing, progression, and physical processes of freeze-up and break-up
during 2012–2014 between tidewater and the Oshetna River confluence (PRM 235.2
[RM 233.4]), using historical data, aerial reconnaissance, stationary time-lapse cameras,
and physical evidence.
• Determine the potential effect of various Project operational scenarios on ice processes
downstream of Watana Dam using modeling and analytical methods.
o Develop a modeling approach for quantitatively assessing ice processes in the
Susitna River.
o Calibrate the model based on existing conditions. Use the model to determine the
extent of the open water reach downstream of Watana Dam during Project
operations.
o Use the model to determine the changes in timing and ice-cover progression and
ice thickness and extent during Project operations.
• Develop detailed models and characterizations of ice processes at instream flow Focus
Areas in order to provide physical data on winter habitat for the Fish and Aquatics
Instream Flow Study (Study 8.5).
• Provide observational data of existing ice processes and modeling results of post-Project
ice processes to the Fluvial Geomorphology Modeling below Watana Dam Study (Study
6.6), Groundwater Study (7.5), Instream Flow Studies (Studies 8.5-8.6), Fish and
Aquatics Study (Studies 9.12), Riparian Vegetation Study Downstream of the Proposed
Susitna-Watana Dam (Study 11.6), Recreation and Aesthetics Studies (12.5-12.7), and
Socioeconomic and Transportation Study (Study 15.7).
• Research and summarize large river ice processes relevant to the Susitna River, analytical
methods that have been used to assess impacts of projects on ice-covered rivers, and the
known effects of existing hydropower operations in cold climates.
Thermal and ice modeling for the reservoir and the general thermal modeling for the river during
the 5 months when ice is not present will be accomplished under the Water Quality Modeling
Study (Study 5.6). The output from that work will be used in this river ice processes study.
Likewise, open water flow routing will be performed under the Fish and Aquatics Instream Flow
Study (Study 8.5), while ice-affected flow routing will be performed by this study.
3. STUDY AREA
The study area consists of the Susitna River between the mouth at Cook Inlet (PRM 0) and the
Oshetna River confluence (PRM 235.2) as indicated in Figure 3.0-1. Observations were
generally organized by river reach, with the Lower River extending from Cook Inlet to the
upstream side of the confluence of the Chulitna, Talkeetna, and Susitna Rivers; the Middle River
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 2 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
extending from the three rivers confluence up to the proposed Watana Dam site; and the Upper
River extending from the proposed Watana Dam site to the Oshetna River confluence.
• Lower River: PRM 0 – PRM 102.4
• Middle River: PRM 102.4- PRM 187.1
• Upper River: PRM 187.1 – PRM 235.2
4. METHODS
This Technical Memorandum describes the components of the ice processes study which
includes aerial observations of ice processes and time-lapse photography.
4.1. Aerial Reconnaissance
Aerial reconnaissance of freeze up progression, open leads, and breakup progression was
completed on the Lower, Middle, and Upper River. Observations of these processes were
completed by visual reconnaissance, photography, and video of the entire 235-mile study area.
Ice processes field observation standards follow those of EM-1110-2-1612, Ice Engineering,
developed by the U.S. Army Corps of Engineers (USACE 2002) and Michel (1971). Aerial
reconnaissance flights included observations of the mainstem of the Susitna River and the
mouths of major tributaries, including the Yentna, Chulitna, and Talkeetna Rivers. A
Geodatabase of ice features was created and includes GPS-referenced photographs and video
from each flight. Daily field summaries provide a narrative of ice processes over time. Open
leads were systematically mapped using a GPS enabled iOS mapping application for use with the
Apple iPad. Both downstream and upstream waypoints were collected for longer open leads,
while for leads less than about 100 feet in length only a center point was located. Georeferenced
photographs were taken of most leads mapped, as well as continuous video. Each lead was
classified as thermal or velocity in origin based on the following criteria:
• Thermal leads were generally found in marginal areas outside of the main channel flow.
These include bank toes, which may accumulate groundwater from the surrounding
floodplain, the margins of gravel bars, side channels, and side sloughs where shallow
upwelling water may occur. Thermal leads were distinguished by very shallow depth
(often bare gravel), discoloration and staining of water (occasional), and uneven, rounded
edges and beaded appearance. In addition, throughout the winter, thermal leads tended to
grow larger, except during very cold periods when border ice might form.
• Velocity leads tend to be in the thalweg of main channel braids, have visible current,
deeper water, occasionally broken ice accumulated along edges or at downstream end,
and the margins were smoother and aligned with current. During cold periods, flowing
frazil would accumulate at the downstream ends of velocity leads.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 3 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
4.2. Time-Lapse Camera Monitoring
Time-lapse cameras monitored freeze up and breakup at locations corresponding to flow-routing
model instrumentation, key ice processes, and fish habitat locations. Time-lapse cameras were
set to take photos of a site at 15-minute intervals, all dark and night shots were removed, and the
resulting images were compiled to create videos. Each site has videos created for both freeze up
and breakup events. Each video was reviewed and a narration created to summarize key
observations. The narrations for each site are found in Section 5.1.1.1and 5.1.2.1 for freeze up
and Sections 5.3.1.1 and 5.3.2.1 for breakup. The narrations include the timing of ice cover
advance and decay, the relative abundance of frazil ice visible in the channel during freeze up,
the growth of border ice during freeze up from the shore, and the local interaction of ice with the
floodplain. The locations of the time-lapse cameras for 2013 freeze up and 2014 breakup are
listed below and in Table 4.2-1 and shown on Figure 4.2-1:
• PRM 13.9, Alexander Slough near Upper Tidal Influence
• PRM 29.8, Susitna Station at ESS20
• PRM 64.2, near Rustic Wilderness, Side Channel
• PRM 65.2, near Susitna Landing
• PRM 91.4, near Birch Creek
• PRM 104.3, Whiskers Slough near FA-104
• PRM 113.2, Slough 6 near FA-113
• PRM 115.4, Slough 6 near FA-115
• PRM 129.6, Slough 8A near FA-128
• PRM 132.2, Slough 9
• PRM 138.5, Slough 11 near FA-138
• PRM 142.2, near Indian River and FA-141
• PRM 145.7, Slough 21 near FA-144
4.3. Meteorological Data Collection
Daily meteorological data were obtained from the National Weather Service (NWS) station in
Talkeetna between October 1, 2013 and June 1, 2014. A tabulation of freezing degree days and
thawing degree days was kept; along with water temperature data from transect stations along the
Lower and Middle River. SNOTEL data were collected during the same period at Susitna Valley
High School, Tokositna Valley, and Point McKenzie. Data were collected at these same sites for
the 2011/2012 and 2012/2013 Ice Processes Study.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 4 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
5. RESULTS
Winter 2013/2014 was characterized by normal flows during early ice formation that continued
to be near normal through fall and early winter as recorded by USGS gages at Tsusena (Figure
5.1-1), Gold Creek (Figure 5.1-2), and Sunshine (Figure 5.1-3). Temperatures during the winter
were at or above historical averages at Talkeetna with generally higher than average
temperatures during the month of January. Temperatures in late winter and spring were mild,
similar to historical averages (Figure 5.1-4).
Overall, freeze-up was characterized by ice progression from downstream to upstream with few
significant jamming or overbank events. Frazil flow was first observed in the Middle River at
PRM 145.7 on October 23, 2013 when a field crew was installing time-lapse cameras. As
temperatures dropped over the Basin, frazil ice production formed bridges with the earliest ice
bridges being short, thick frazil ice bridges in Devils Canyon, which did not progress upstream.
Again, ice cover in the Lower River was initiated by bridging in the lower 5 miles of the River
which was similar to observed freeze-up in 2012. The Lower River ice cover progressed steadily
to the Three Rivers confluence then slowed as it progressed farther upstream. Ice cover on the
upper reaches of the Middle River and Upper River formed and progressed steadily upstream
until the River was primarily ice covered by the end of December 2013. Figures 5.1-5 and 5.1-6
illustrate the ice front progression and ice bridge locations as observed over freeze-up in 2012
and 2013, respectively.
Breakup 2014 was characterized by mild temperatures and a gradual melt-out of the ice and
snowpack in the Susitna Basin. Temperatures for late winter and spring followed historical
averages at Talkeetna. The peak of breakup occurred the weekend of May 3, 2014 with mostly
rotten ice cover flowing from the River with the only remaining ice cover observed at PRM 206-
223 through May 8.
5.1. Freeze-up Observations
Freeze-up aerial reconnaissance of the 234-mile study reach began on November 6, 2013
following the first observed floating frazil ice and finished on December 23 when the ice cover
progression approached its maximum extent. On November 6, frazil ice was observed flowing
throughout the entire river except for the lower sections of the Lower River. Border ice was
observed in early stages of growth with few constriction sites in the Middle and Upper River. Ice
bridging locations were observed in the upper reaches of the Middle River and in few locations
of the Upper River. Two short ice covers were present; one in the Middle River and one in the
Upper River. Border ice continued to grow and frazil production appeared steady throughout the
River. A bridge at the mouth was first observed on November 12 and the ice front progressed
steadily upstream as shown in Figure 5.1-7. Bridging locations were observed, in addition to
sections of ice cover, in the upper section of the Middle River and intermittently through the
Upper River and continued to accumulate more ice. The flight on November 19 followed a sharp
temperature drop which fueled frazil production and ice cover growth on the River. Heavy frazil
production and movement downstream was observed throughout most open channels in all
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reaches of the River. The period of continued cold persisted through the end of November and
the ice front passed Talkeetna by November 25. The month of December brought fluctuating
temperatures but the Susitna River freeze-up progression neared its maximum extent by
December 23. Continued cold weather and frazil deposition filled in most of the open reaches
remaining.
5.1.1. Lower River Observations
November 6: Frazil ice was first observed at PRM 39.5 and was intermittent throughout the
entire Lower River reach.
November 8: Frazil ice continued to move down the river and reached the Cook Inlet. Most of
the river was covered with upwards of 50 percent surface concentration of frazil ice.
November 12: An ice bridge formed at the mouth of the river and the ice front had progressed to
PRM 29.8 since the previous flight on November 8. The ice cover was formed from
consolidated pans on the main channel while many side channels were open through the
highly braided reach. Frazil continued to move into the Lower River and was observed
through most open channel locations as shown in Figure 5.1-8. Border ice growth on the
Lower River was isolated but present.
November 15: The ice front progressed 19 miles to PRM 48.8. Both mouths of the Yentna and
Deshka Rivers were frozen with rough, consolidated frazil ice covers.
November 19: Cold air temperatures caused dense fog along open water sections on the Lower
River making observations from the air difficult. Several ice bridges were observed on the
main channel in this highly braided section with one continuous ice cover from PRM 72.2-
74.6. Frazil was observed in most open water in the Lower River. The Talkeetna River was
observed to be frozen at the confluence with the Susitna River.
November 21: Open leads were observed in the Lower River ice cover. Leads were primarily
velocity in origin with several potentially thermally influenced leads in highly braided
sections close to banks. A large open section of water was observed directly south of the
airport near Talkeetna at PRM 99.
November 25: Ice cover stretched over the Lower River with open water designated as thermal
or velocity leads with no other significant open sections. Overflow was observed in several
locations. The mouth of the Chulitna River was frozen over at the confluence with the
Susitna.
November 29: No significant changes were observed on the Lower River from the previous
flight. Open leads remained present and frazil was observed in the open leads.
December 3: Open leads on the Lower River were generally similar to the last flight being long
and narrow in the thalweg and short and narrow with apparent thermal input near banks in
highly braided sections. Frazil was observed being produced in long and narrow open leads
in thalweg of main channel.
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December 12: Open leads on the Lower River were generally similar to the last flight being long
and narrow in the thalweg and short and narrow with apparent thermal input near banks in
highly braided sections. Frazil was observed being produced in long and narrow open leads
in thalweg of main channel.
December 18: The Lower River continues to be ice covered with little sign of change from the
previous flight.
December 23: The Lower River continues to be ice covered with little sign of change from the
previous flight.
5.1.1.1. Lower River Time-Lapse Cameras
PRM 13.9, Alexander Slough near Upper Tidal Influence: The camera was installed on
October 21, on the right bank, in a large cottonwood tree with a general upstream view.
Floating frazil was first observed on November 7 at 9:00am, which was the first image of the
day. Frazil concentration continued to increase over the next two days until the frazil ice
stopped moving as observed in the first image of November 9 taken at 9:00am. River stage
visibly increased over the next nine hours but no overflow was observed. By November 11
the entire channel was ice covered with a combination of consolidated frazil and thermally
grown border ice. The site experienced small overflow events during the winter including
December 5, January 3 and 31, and February 27. No other events were observed.
PRM 29.8, Susitna Station at ESS20: The camera was installed on October 16, on the left bank,
in a birch tree on the same bluff that the USGS gage is located, roughly 50 feet above the
river surface. The view was upstream towards the single, main channel. Low concentration of
floating frazil was first observed on November 6 at 3:45pm. By November 7 surface frazil
concentration sharply increased to 50 percent and continued to increase until observation of
stopped ice flow at 12:00pm on November 12. The ice cover consolidated and no movement
was observed following the cover formation. No overflow or stage increase were observed,
likely due to the elevation difference between the camera site and the ice surface.
PRM 64.2, near Rustic Wilderness Side Channel: The camera was installed on October 21 on
the right bank, on a small island in the highly braided section of Rustic Wilderness, farthest
away from the mapped main channel. The camera view was across the main channel towards
the left bank of the river. Floating frazil was first observed on November 6, with the first
image of the day at 9:30am. A very gradual increase in frazil concentration between 5
percent and 25 percent surface concentration was observed through November 14 when frazil
concentration decreased. During the afternoon of November 17, the channel nearest the
camera froze over with a high thermal influence in conjunction with frazil accumulation. A
stage rise and surface frazil concentration increase were observed at 5:00pm on November
18. The stage rise was assumed to have continued through the night and the channel became
ice covered as the first image of the day on November 19 showed all channels covered. A
small overflow was observed on November 25. No other events were observed.
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PRM 65.2, near Susitna Landing: The camera was installed on October 16 on the left bank in a
small birch tree with a general upstream view, nearest the mapped main channel. Frazil was
first observed at low surface concentration on October 24, but was no longer visible during
the late morning of October 25. Frazil begin flowing again on November 6 and surface
concentration gradually increased from 5 percent to 40 percent between November 6 and 18.
Frazil ice accumulated and a cover formed at 5:45pm on November 18. No further changes to
the ice cover were observed.
PRM 91.4, near Birch Creek: The camera was installed on October 21 at the exit of Birch Creek
(slough) into the Susitna on the left bank with a general upstream view. Frazil was first
observed on November 6 at 25 percent surface concentration but stopped in the morning of
November 7. The channel froze over from thermally grown smooth border ice, with the cover
complete on November 17. Numerous overflow events occur, with a persistent open lead
present on the right bank of the main channel.
5.1.2. Middle River Observations
November 6: The Middle River generally showed flowing frazil at 50 to 75 percent
concentration with a few constrictions but no ice bridges or covers below Devils Canyon.
Bridging locations, including one notable ice cover, were present in Devils Canyon and just
downstream of the dam site.
November 8: Lower reaches of the Middle River continued to see frazil transport with border ice
visible in many areas. Heavy frazil production combined with border ice growth in specific
areas began constricting the open channel and added to bridging in the upper reaches of the
Middle River as shown in Figure 5.1-9.
November 12: Lower reaches of the Middle River were very similar to those of the Lower River
except with an increase in border ice growth. The first ice bridge was encountered upstream
of Portage Creek at PRM 152.8 and several small ice covers and ice bridges were observed
through Devils Canyon. Open channel dominated between Devils Canyon and the dam site
with a single ice bridge at PRM 183.7.
November 15: The Middle River continued to show signs of border ice growth with the main
channel and few side channels open. Above Portage Creek, ice bridges and short ice covers
present on the previous flight remained in place. Ice cover appeared lumpy from frazil pan
accumulation as opposed to smooth in texture.
November 19: Observations on the iPad were collected only through PRM 136 at which time the
cold temperatures rendered the device ineffective. The same was true for the video camera on
the front of the aircraft. Still images and notes in field books were collected for the remainder
of the flight. Heavy frazil flow and accumulation into frazil trains was observed through the
Middle River with ice bridges and cover forming in Devils Canyon. Frazil was lighter
upstream of Devils Canyon allowing anchor ice to be more visible. Border ice and anchor ice
growth appeared increased from the previous flight through. An ice cover was present
through the dam site canyon.
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November 21: Heavy frazil ice dominated observations in the lower section of the Middle River
with ice bridges and covers appearing upstream of Devils Canyon.
November 25: Reduction in frazil allowed for better observations of anchor ice formations
present in many locations along the Middle River. The ice bridge cover on November 21
from PRM 163.2-164.3 had collapsed and only a bridge remained on November 25 at PRM
163.3. Nearly all other covers and bridges were the same as the previous flight.
November 29: The Middle River exhibited increased frazil from the previous flight, but bridging
locations did not change from the previous flight. Devils Canyon showed more signs of
jamming and releasing with shearwalls visibly increased in size.
December 3: Ice cover on the Middle River increased in the reach downstream of Devils
Canyon. Open water in the Middle River was moving frazil downstream and anchor ice was
visible through most open reaches as shown in Figure 5.1-10. Through Devils Canyon to the
dam site, ice bridges and cover were similar in location and extents.
December 12: The ice front progressed only a few more miles upstream from observations on
the previous flight and the ice cover upstream of FA 128 progressed a few miles as well. Ice
covers and bridges in Devils Canyon were similar in length and location to the previous
flight.
December 18: The ice front progressed to PRM 119.2 and the ice cover starting at FA128
extends up to PRM 148.5 which was an 8 mile extension from the previous flight. Devils
Canyon continued to show signs of jamming and releasing with significant shearwalls and
stranded ice present as shown in Figure 5.1-11. An ice cover remained intact through the dam
site.
December 23: The ice front progressed to PRM 122.0 and the ice cover starting at FA128 has
jammed and released, opening a section that was covered during the previous flight. Devils
Canyon continues to show signs of jamming and releasing with significant shearwalls and
stranded ice present. An ice cover remained intact through the dam site and has met the
Upper River ice cover leaving the Susitna River ice-covered above PRM 185.5.
5.1.2.1. Middle River Time-lapse Cameras
PRM 104.3, Whiskers Slough near FA-104: The camera was installed on October 25 on the
right bank while frazil was observed in the river. The camera view was upstream. Border ice
begins growing on October 26 in conjunction with increased frazil flow but the frazil stopped
and the border ice washed out on October 28. Continuous frazil flow resumed on November
5 and steadily increased from 25 percent to 75 percent surface concentration between
November 5 and 21. During the night of November 21, the ice front passed the camera site
and left remnants of a large freeze up jam with the ice cover remaining being very jumbled
and rough in texture with notable stage rise observed. Following consolidation of ice, no
further events were observed.
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PRM 113.2, Slough 6 near FA-113: The camera was installed on October 25 on the left bank of
the main channel on an island looking across the main channel towards the right bank. Frazil
was observed in the river during installation, yet the frazil stopped on October 27. November
5 saw the return of frazil flow and the surface concentration continued to increase from 5
percent to 75 percent until November 23. During the afternoon of November 23, a sharp
reduction in frazil concentration occurred; dropping from 75 percent to 10 percent surface
concentration. Frazil concentration again gradually increased, from 10 to 50 percent, through
the morning of December 3 at which time the stage began to rise and by 3:15pm the ice front
was observed moving past the camera site. Within 1 hour and 45 minutes the ice front
progressed past the site, leaving the channel ice covered, and the stage continued to rise
causing minor flooding and overflow through 10:00am December 6. By December 6, the ice
cover was consolidated and no further events were observed.
PRM 115.4, Slough 6 near FA-115: The camera was installed on October 23 on the right bank,
just downstream from a slough entrance, and looking upstream at the main channel. Frazil
was first observed on October 24 at a 10 percent surface concentration but ceased on October
27. November 5 was the return of frazil to the site at a 5 percent concentration and quickly
jumped up to 25 percent on the morning of November 6 and persisted till November 14 when
the surface concentration dropped to 10 percent. Between November 14 and 22 surface
concentrations steadily increased from 10 to 75 percent, yet on the morning of November 23
a sharp reduction in frazil brought the surface concentration down to 10 percent. Frazil
concentration fluctuated between 10 and 50 percent through December 12 and the first image
of the day on the morning of December 13 revealed the channel to be ice covered. By the
afternoon of December 13 the stage rise associated with the ice front passing the site stopped
and the ice cover consolidated. There were two consolidation events associated with shifts in
the ice cover; one shift in the ice cover on December 14 and a significant shift between
5:00pm and 5:15pm on December 16 that left the ice cover very broken and jumbled with an
increase in ice surface elevation. No further events were observed.
PRM 129.6, Slough 8A near FA-128: The camera was installed on October 23 on the left bank
of the main channel with a view generally upstream. A short-lived run of frazil at 25 percent
surface concentration occurred between October 24 and 27 with continuous frazil flow
resuming on November 5 at a 25 percent concentration. Between November 5 and 30 frazil
concentration steadily increased to a maximum of 75 percent and during the afternoon of
November 30 the ice front was observed moving past the camera site. In the time between
4:00pm and 4:15pm, the river went from flowing frazil to ice covered. Between 4:30 and
4:45 a stage rise was observed with ice consolidating during that time. Following the
consolidation, no further events were observed.
PRM 132.2, Slough 9: The camera was installed on October 25 on the left bank with a view
across and slightly upstream on the main channel. Frazil was present in the river during
installation but ceased during the night of October 27. Frazil resumed on November 5 at a 10
percent surface concentration and jumped to 50 percent on the morning of November 6. The
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surface concentration remained at 50 percent until 5:00pm November 16 when the camera
malfunctioned and stopped recording images.
PRM 138.5, Slough 11 near FA-138: No images were collected during freeze up due to
equipment malfunction.
PRM 142.2, near Indian River and FA-141: The camera was installed on October 23 just
upstream of the Indian River confluence on river right bank with a view across and slightly
upstream on the main channel. Frazil was first observed between October 24 and 27 with
surface concentration increasing from 10 to 25 percent but stopped on October 27. Frazil
flow resumed on November 5 and increased in concentration from 10 percent to a maximum
of 75 percent on November 10 and 11 and then began steadily reducing to below 5 percent
surface concentration on November 14. Between November 14 and December 14 frazil
concentration fluctuated between 10 and 75 percent and then during the night of December
14 the ice front passed the camera site with the first image of the day on December 15
showed the channel 100 percent covered. During the afternoon of December 21 the stage
visibly increased and raised the ice surface elevation. An open lead began forming shortly
after the stage increase in the main channel and remained open until February 9. A small
open lead formed near the bank on December 28 and appeared to be thermal in origin. This
open lead experienced several ice covers but seemed to always return to an open state. A
cover formed on January 13 but opened on January 16 and again on February 9 but opened
on February 28 and remained open. No other events were observed.
PRM 145.7, Slough 21 near FA-144: The camera was installed on October 23 on the left bank
with a view across main channel and within one hour of installation frazil flow was first
observed. Frazil stopped flowing during the night of October 28 and did not resume flowing
until November 4. Surface frazil concentration fluctuated between 10 and 75 percent from
November 4 until November 30 when an ice front progressed past the camera site. The ice
cover was short-lived as it flushed out 60 minutes after forming. The open main channel
fluctuated between 10 and 50 percent surface frazil concentration from November 30 to
December 16. The morning of December revealed an ice cover and stage increase. The ice
cover shifted and consolidated over the day and remained undisturbed until December 21
when the first image of the day showed a large stage rise resulting in a very jumbled and
shifted ice cover. No further events were observed.
5.1.3. Upper River Observations
November 6: The Upper River was similar to the Middle River with 50 to 75 percent flowing
frazil, several constrictions with frazil still moving and few bridging and cover locations.
November 8: Ice cover in the Upper River continues to grow and connect between bridging
locations. Signs of one freeze up jam were observed near PRM 197.5.
November 12: Ice cover on the Upper River continued to grow with the most significant cover
over 17 miles long. Signs of freeze up jams were present with very rough ice cover and
several pressure ridges formed across the channel indicating jamming locations.
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November 15: Ice bridges observed during the previous flight had grown into significant ice
covers observed during this flight. Overall, the ice cover appeared rough from frazil
accumulation with few areas appearing to have experienced freeze up jamming. Little frazil
production and floating frazil were observed in open channels, although slightly more than in
the Lower and Middle River.
November 19: Anchor ice and border ice growth as shown in Figure 5.1-12 continued on the
Upper River and was present through most open water sections. A significant ice cover
stretched from PRM 207 to 218.
November 21: The Upper River ice cover started around PRM 190 and continued to extend
upstream with constant frazil production. Observation ended at PRM 210 as daylight was
diminishing and the field team turned around.
November 25: The Upper River ice cover beginning at PRM 189 was still present but the field
team did not observe the extent of the cover due to the short daylight and had to turn around
at Watana Creek.
November 29: The Upper River ice cover beginning at PRM 189 was still present but again the
team was not able to observe the extent of the cover due to short days and turned around at
PRM 212. They commented that the cover extended as far as they could see, but no definite
river mile was observed.
December 3: The ice cover on the Upper River was finally observed in its entirety as the team
was unable to fly to the Oshetna River confluence since November 15. No observation of the
rate of progression was able to be collected, but the cover extended over 30 miles of the
river.
December 12: The Upper River was primarily ice covered. The cover had numerous open leads
throughout and all appeared to be velocity in origin with defined down- and upstream ends.
Upstream of Vee Canyon appeared to be continuously open, past the Oshetna confluence.
December 18: The Upper River remains primarily ice covered with little change from the
previous flight.
December 23: The Upper River remains primarily ice covered with little change from the
previous flight.
5.1.3.1. Upper River Time-Lapse Cameras
No time-lapse cameras were installed in the Upper River during the 2013/2014 winter field
season due to lack of land access.
5.2. Open Lead Mapping
Two open lead mapping events occurred during late winter and early spring 2014; February 20-
21 and April 2. Open leads from PRM 0-235.2 were mapped aerially and documented using
GPS-enabled cameras. The limited daylight in February required two flights to complete the
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mapping with PRM 140 – 235.2 mapped on February 20 and PRM 0 – 187.2 mapped on
February 21 providing for some overlap. The temperatures for Talkeetna during the February
survey ranged from -23o C to a high of -7o C. In April, the temperatures (also recorded in
Talkeetna) ranged from -12o C to a high of 5o C. Generally, long narrow velocity leads were
observed in the thalweg in each reach of the river while shorter and narrower thermal leads were
observed in the Lower and Middle River near gravel bars and braided sections. The Upper River
was mostly ice covered athough there were thin velocity leads in the thalweg and some thermal
input at the mouths of tributaries.
5.2.1. Lower River
Open leads in the Lower River during the February 21 and April 2 surveys included both those
of velocity and thermal origin. In general, the velocity leads were either located in the main
channel thalweg or on the outside of bends as shown in Figure 5.2-1. Several of these velocity
leads could be characterized as elongated ‘holes’ caused by turbulence or upwelling water.
Some of the side channels/sloughs were introducing warmer water, resulting in small thermal
leads that would often blend into a velocity lead in the main channel. The thermal leads were
either groundwater upwelling in the bottom of a side channel or slough, groundwater seepage off
of bluffs/ river banks (Figure 5.2-2), from upland sources, or input from tributaries.
During the February 21 survey, 10 thermal leads and 41 velocity leads were mapped on the
Lower River. Frazil ice was being generated and accumulating in many of the velocity leads.
On the April 2 survey, 12 thermal leads and 27 velocity leads were mapped. Many of the
velocity leads identified during the February survey had narrowed and/or closed due to cold
weather and dropping discharge in March. Rising temperatures in late March/early April allowed
groundwater sources to widen areas of open water in side channels/sloughs and braided sections.
5.2.2. Middle River
The Middle River had a similar pattern of leads as the Lower River although there were more
thermal leads coming from sloughs with groundwater origins. An example of these sloughs and
beaver ponds can be seen at FA-104 (Whiskers Slough) as shown in Figure 5.2-3, FA-115
(Slough 6A), and FA-128 (Slough 8a). Some of the open velocity leads extended almost to the
full channel width and these were often connected with sections of ice cover such that the reach
was characterized as an intermittent open lead/reach. Several of these sections were quite long,
sometimes extending for up to a mile in length. As with the Lower River, thermal leads running
along a bank or side slough often combined with a velocity lead at its upper end.
On February 20-21 (there was coverage of PRM 140 – 187.2 on both days), 18 thermal leads, 45
velocity leads, and 5 velocity leads that were characterized as open channel sections were
mapped. Frazil and anchor ice were observed in most of the velocity leads and open channel
sections.
On April 2, 18 thermal leads were again mapped but the velocity leads and open channel sections
had narrowed and frozen over to give a total of 27.
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5.2.3. Upper River
In the Upper River almost all of the leads were velocity in origin as shown in Figure 5.2-4.
Thermal input could be seen only at the mouths of tributaries which were mostly were frozen
over. Groundwater contribution through seepage from upland sources showed up as small
glaciated features flowing off the banks.
On February 20, only one thermal lead was mapped. Open channel or velocity leads accounted
for 19 additional mapped features. The temperature in Talkeetna had dropped down to -23o C the
night before our survey and there was a lot of Frazil and anchor ice observed in the Upper River.
On April 2, again, only one thermal lead was mapped. Open channel or velocity leads continued
to show a decrease in number from the February 20 survey due to cold temperatures with
narrowing or total closure of many leads. A total of 8 leads or open channel features were
mapped.
5.3. Breakup Observations
Breakup aerial reconnaissance of the 235-mile study reach began on April 14, 2014 (not long
after the the last open lead mapping) and finished on May 8 when the main channel of the river
was ice free. On April 14 the River showed initial signs of warmer temperatures with signs of
melting including reduced snow cover on the ice and overflow downstream of open water
sections. Gradual melting and deterioration of the ice cover continued through the end of April
with mild temperatures and generally constant discharge and water levels observed. The flight on
May 2 followed a week of warm weather in the basin and noticeably higher water levels were
observed but no significant changes to ice cover were observed from the previous flight.
Following the flight on May 2, ice conditions continued to deteriorate and breakup began in
earnest. Inspection of the remote cameras at the ESS sites showed that the ice cover at Susitna
Station began to breakup and pass downstream at approximately 10 PM on May 2 with a large
run past the site (likely most of the Yentna and Lower River ice) passing between noon and 5
PM on May 3. The ice cover at Curry, PRM 124, broke up and passed downstream at 7-8 AM on
May 3. The ice cover at Portage Creek broke up and passed downstream around 9-10 PM on
May 2. An ice run passed by Fog Creek, ESS65 at PRM 176.4, around 5 PM on May 2, likely
the same run that was witnessed just before at ESS80, PRM 225, during the May 2 flight. There
was an ice jam that formed just below ESS40, upstream of FA104 - Whiskers Slough, at
approximately 10AM on May 3, with a significant rise in water levels and some overbank
flooding. This jam extended upstream from about PRM 105.5 to 108. The jam failed and passed
downstream at approximately 5PM on May 4. The flights on May 5 and 8 revealed much of the
ice had gone out on the River with the only significant cover present between PRM 206 and
PRM 223. The May 8 flight traveled upstream of the Oshetna Confluence to assess ice cover in
the upper reaches of the River. The upper reaches of the river appeared to have ice cover intact,
but was open to the MacLaren River at PRM 265.
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5.3.1. Lower River Observations
April 14: The mouth was open from tidal action but very few open leads were present in the
main channel until PRM 65 near Susitna Landing. Numerous snow machine tracks and a few
snow machines were spotted on the ice near Susitna Landing. Between Susitna Landing and
Talkeetna the river was showing signs of melting with overflow present downstream of open
leads. Many of the sloughs had open water due to the ice cover collapsing over the channels.
This was the case for the Birch Creek area. At Talkeetna, a long and fairly wide open
lead/open channel was present with ice chunks present in the downstream end, a sign of
early-stage breakup. This open water section was along the river left bank and extended from
the Three Rivers Confluence to directly south of the airport (PRM 101 to 99). The Talkeetna
River was open upstream of the railroad bridge. The Chulitna River had several small and
narrow open leads at the confluence with the Susitna but otherwise appeared to have a solid
ice cover.
April 21: The mouth was open from tidal action to PRM 4. Leads were opening up in the main
river channel; however they remain small and narrow in the main channel below PRM 65
near Susitna Landing. Many side channels and sloughs were showing signs of melting with
water on the ice surface along the banks and following the thalweg. Between Susitna
Landing, PRM 65, and Talkeetna, PRM 100, the river was showing signs of melting with
overflow onto the ice surface downstream of open leads. The open leads had increased in
length and connectivity and in some areas around the islands there were networks of braided
thermal and velocity leads. At Talkeetna, just off the approach end of runway 36, the long
and fairly wide open lead continued to extend to the confluence with the Chulitna. Both the
width of the lead and amount of ice accumulated in the downstream end had increased from
the previous flight. The Talkeetna River was open upstream of the railroad bridge but had not
opened at the confluence with the Susitna. The water level in the Chulitna River was still low
and several small and narrow open leads at the confluence persisted.
April 23: The mouth was open from tidal action to PRM 4. There were short open sections
developing where the cover has locally moved downstream at PRM 8, 10.2, and 13.5. Above
PRM 15 the cover was generally intact but it was visibly rotting. In the Delta Islands area,
PRM 46, there were many thermal leads and open channels. The thalweg in most reaches
shows some overflow and the cover was still depressed; meaning the flow can increase
considerably prior to totally filling the thalweg channel. Open leads were widening and
lengthening in the main channel between Susitna Landing, PRM 65, and Talkeetna, PRM
100. At Talkeetna, just off the approach end of runway 36, the wide open lead continued to
increase in length as well as the amount of broken ice in the downstream end. The Talkeetna
River remained open past the railroad bridge and only a short section of ice remained at its
confluence with the Susitna. The water level in the Chulitna River was still low and there
were several very small and narrow open leads at the confluence with the Susitna.
April 25: The mouth was open from tidal action to PRM 5 where there was a short section of ice
cover. The east channel was still covered in ice, but the main channel was open with remnant
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ice cover along the left bank. The intact ice cover begins at PRM 16.5 above Alexander
Slough. The Yentna River was ice covered at the confluence of the Susitna River. Kroto
Slough was open at its confluence with the Yentna due to thermal melt, but was still ice
covered at the upstream confluence with the Susitna River. Through the Delta Islands, PRM
46, there was again a significant increase in the open interconnectivity of the thermal leads in
off channel sections, which created braided flow channels that were discharging into to the
main channel of the Susitna River. Open leads continued to widen and lengthen in the main
channel between Susitna Landing, PRM 65, and Talkeetna, PRM 100. Sporadic short
sections of open channel were beginning to appear. Ice had accumulated in the downstream
ends of the open channels, but water levels upstream of the ice accumulation had not
noticeably increased. At Talkeetna, off the approach end of runway 36, the wide open lead
continued to increase in length to the point it was almost open channel in places. The amount
of broken ice in the downstream end remained unchanged. The Talkeetna River still had not
breached the confluence with the Susitna River, but was open upstream of the railroad
bridge. The water level in the Chulitna River was still low, but the small and narrow open
leads present on April 23 at the confluence with the Susitna had become larger.
April 28: The mouth was open and the short section of ice cover observed on April 25 was gone.
The intact ice cover began at PRM 16.5 above Alexander Slough as shown in Figure 5.3-1.
The Yentna River was still ice covered at the confluence of the Susitna River. Through the
Delta Islands, PRM 46, there was again a significant increase in the open interconnectivity of
the thermal leads in off channel sections, creating braided flow channels that were
discharging into to the main channel of the Susitna River. Open leads continued to widen and
lengthen in the main channel between Susitna Landing, PRM 65, and Talkeetna, PRM 100.
Larger ice chunks were building up in the downstream ends of the open channels; water
levels were starting to rise upstream of these developing jams. At Talkeetna, off the approach
end of runway 36, the open lead had grown enough to be considered an open channel. The
developing jam in the downstream end was larger and the water was rising all the way up to
the Chulitna confluence. The Talkeetna River stage has increased yet still had a small section
of ice separating it from the Susitna as shown in Figure 5.3-2. The water level in the Chulitna
River was slightly higher and open leads at the confluence with the Susitna had become
larger.
April 30: The mouth was open to PRM 16.5 above Alexander Slough. The Yentna River was
still ice covered at the confluence of the Susitna River. Through the Delta Islands, PRM 46,
there was again a significant increase in the open interconnectivity of the thermal leads in off
channel sections, creating braided flow channels. Open leads continued to widen and
lengthen in the main channel between Susitna Landing, PRM 65, and Talkeetna, PRM 100.
Many sections had become open channels separated by accumulations of ice chunks. At
Talkeetna, the open channel extended about a mile farther downstream to PRM 98. The
Talkeetna River had breached the confluence with the Susitna and the channel was open
upstream under the bridge. The open main channel of the Susitna now extended up to the
Chulitna confluence.
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May 2: The Susitna River was open from the mouth to approximately PRM 25. Sloughs and side
channels were also open. The Yentna and Susitna confluence was still ice covered but the ice
surface was showing signs of significant melt and rotting. In the Delta Islands area there were
many thermal leads and open channels with some longer sections of open river. Open leads
had widened and lengthened in the main channel between Susitna Landing, PRM 65, and
Talkeetna, PRM 100, with significant open reaches from the Sunshine Bridge all the way to
Talkeetna. The Talkeetna River was open past the railroad bridge. The water level in the
Chulitna River had increased and there were several open leads and channels at the
confluence with the Susitna.
May 5: The Lower River was open through the entire reach with shorefast ice in a few places
and remnant chunks and brash along the banks. The Lower River had entered spring as many
trees seemed to have budded out leaves over the weekend. USGS gage readings at Susitna
Station as of May 7 indicated flows upwards of 80,000 CFS. Both the Chulitna and Talkeetna
Rivers appeared open, and the Chulitna River had more shorefast ice on gravel bars.
May 8: The Lower River was open through the entire reach with remnant chunks and brash ice
along the banks. USGS gage readings at Susitna Station as of May 9 indicate instantaneous
flows of 82,600 CFS. Both the Chulitna and Talkeetna Rivers were open, and the Chulitna
River had more ice chunks and brash on gravel bars.
5.3.1.1. Lower River Time-Lapse Cameras
PRM 13.9, Alexander Slough near Upper Tidal Influence: Evidence of tidal action was present
at the site with visible stage rise occurring roughly one hour following high tide as measured
at Port Mackenzie. Early April saw tides upwards of 32 feet above mean lower low water.
This tidal action in combination with increasing solar radiation aided in weakening the ice
cover which had no snow cover for insulation. Open water was first visible near shore to the
camera on April 14 and continued to melt through April 17 when the first brash ice
accumulated in the open water. As the water level subsided, corresponding to low tide, water
velocity increased and cracks perpendicular to the current formed followed by a large shift in
the cover early in the afternoon of April 17. The ice cover continued to shift and
reconsolidate on April 18 and 19 and finally flushed out early in the evening of April 19. Ice
floes from upstream passed the site with significant ice passage occurring on April 24, 29,
May 1, 2, and 3. The ice runs on May 1 and 3 were the largest, which left ice stranded on the
banks and bars and covered the entire channel with ice while it was passing the site. By May
4 all ice was clear of the site.
PRM 29.8, Susitna Station at ESS20: Snow covered the ice through most of April with signs of
snow melting and pooling on top of the ice cover at several locations. Ponding of water was
most notable April 16 over much of the ice cover across the entire channel. The ice cover
remained intact and unmoved until the evening of May 2 when three quarters of the ice cover
shifted and began to move downstream. By noon on May 3, the ice cover moved out of the
site and large ice runs from upstream moved through the site. By the evening of May 3 most
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of the significant upstream ice had moved past the site with only small brash passing the site
for the remainder of time the camera was in place.
PRM 64.2, near Rustic Wilderness Side Channel: Snow covered the ice through most of April
with meltwater beginning to pool during the evening of April 16. Gradual melting of the
snow cover continued through the end of April. April 30 brought the first view of open water.
The far side of the channel, left bank of the river, began to open with visible brash
movement. On May 2, a large accumulation of breakup debris covered the open channel,
which increased the stage and caused the mid channel ice cover to to flush out. The channel
nearest the camera opened only a few hours after the mid channel opened. The remnant ice
cover was flushed out during the early afternoon of May 3. Brash and breakup debris
accumulations covered between 50 and 100 percent of the channel for the remainder of May
3 and by the end of the following day the entire channel was open.
PRM 65.2, near Susitna Landing: The fist melting snow pooling on the ice cover was observed
on April 7. The snow cover continued to gradually melt through the remainder of April. On
April 23 a small hole formed in the ice and high velocity water was observed upwelling from
the hole. By the end of the day on April 24 the near bank ice cover visibly weakened and a
narrow open water section appeared. A large section of ice flushed from the site on the
evening of April 29 and the remaining shorefast ice on the far right bank, flushed out by noon
on May 1. A large ice floe moved through the site during the afternoon of May 2, stopped
and began accumulating more ice and consolidating through the end of the day May 3. The
first image of the day on May 4 revealed the channel clear of ice with remnant ice chunks
stranded on the far bank.
PRM 91.4, near Birch Creek: The site experienced a gradual melt out and no jamming or
accumulation of ice was observed at the site. No ice floes were captured in any of the images
which were taken every 15 minutes. The main channel gradually opened with the first
flowing water visible on April 5 and the entire channel was ice free on May 3. No ice floes,
stage increases, accumulations, or other dynamic events were observed.
5.3.2. Middle River Observations
April 14: Sloughs and side channels were opening with long, narrow open leads. FA-104 and
FA-128 both had significant open water in the sloughs, though only small open leads were
present in the main channel. FA-128 had a long open lead in the slough running nearest the
railroad (Slough 8A). This lead was open for a significant length of the focus area (over 3
miles). The main channel appeared to have collapsed in numerous areas, posing on-the-ice
navigation hazards as low water levels were not supporting the ice covers. Above Portage
Creek and through Devils Canyon the river presented remnants of many freeze up jams,
overflow, and refreezing. Above Devils Canyon to the dam site had a fairly continuous ice
cover with only few open leads in the main channel and sloughs. Ice conditions at the dam
site appeared solid with remnants of overflow that had refrozen.
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April 21: The Middle River presented more signs of melting with many of the sloughs and side
channels opening with long, narrow open leads. There was more connectivity between the
open leads and the ice cover showed visible signs of rotting. FA-104 (Whiskers Slough) and
FA-128 (Slough 8A) both had significant open water in the sloughs, although open leads in
the main channel remained small and narrow. Slough 8A, Upper Side Channel 8A, and
Middle Side Channel 8A in FA-128 were almost entirely open. The main channel had
collapsed in many places, resulting in narrow open sections following the thalweg. Above
Portage Creek and through Devils Canyon the river was a combination of wide open leads
and short ice covered sections with some reaches within the Canyon showing signs of
significant opening. Shear walls in the canyon had begun to calve off into the center channel
and ice accumulations were forming in the downstream end of open water sections. Devils
Canyon to the dam site had a fairly continuous ice cover, however that cover was starting to
be compromised with narrow open leads and overflow in the thalweg. The side channels and
sloughs showed increased signs of opening. Ice conditions at the dam site were still solid but
the thalweg had become more depressed with active flooding and overflow on the ice
covered channel.
April 23: The Middle River continued to show more signs of melting with many of the sloughs
and side channels continuing to open with long, narrow open leads. There was more
connectivity between the open leads and the ice cover showed visible signs of rotting.
Openings in the thalweg showed increased stage both directly through water level increase as
well as an increase due to chucks of border ice accumulation at the downstream ends of the
openings. FA-104 (Whiskers Slough) and FA-128 (Slough 8A) both had significant open
water in the sloughs, with the open leads in the main channel becoming more pronounced.
Slough 8A, Upper Side Channel 8A, and Middle Side Channel 8A in FA-128 were almost
entirely open. Above Portage Creek and through Devils Canyon the river was a combination
of wide open leads and short ice covered sections. Shear walls in the canyon continued to
calve off into the channel. Above Devils Canyon there was a long reach of open channel with
brash floating downstream. Between PRM 180 and the dam site there was a continuous ice
cover, but narrow open leads and overflow were present in the thalweg through this reach.
April 25: Melting continued in the Middle River with sloughs and side channels continuing to
open. Some of the long, narrow open leads identified during the previous flight had become
sections of open channel. There was more connectivity between the open leads and open
channels through sections of ice cover. Open channels at the thalweg continued to flow at
increased stage. Border ice along the banks had broken off and was accumulating in the
downstream end of open leads and channels. FA-104 (Whiskers Slough) and FA-128 (Slough
8A) both were open. Slough 8A, Upper Side Channel 8A, and Middle Side Channel 8A in
FA-128 were entirely open but Lower Side Channel 8A remained ice covered as shown in
Figure 5.3-3. Above Slough 8A the Susitna remained ice covered with open leads increasing
in width. Through Devils Canyon, the river was mostly open. Most ice bridges had collapsed
and remnant ice covers were rotting in place. Shear walls in the canyon continued to calve
off; overall the channel had become wider. Above Devils Canyon, a long reach of open
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channel extended noticeably farther upstream than during the previous flight. Numerous ice
chunks were moving downstream. The continuous ice cover started below the dam site, but
narrow open leads and overflow in the thalweg channel increased since April 23. Water
levels remained low in the upper reaches of the Middle River.
April 28: The Middle River stage showed signs of starting to rise. Most of the sloughs and side
channels were completely open. Long, narrow open leads identified during the previous
flight became sections of open channel. Much of the main channel was flowing at almost the
open channel width with large sections of ice collapsed into the open water. Much of the
border ice had broken off and accumulated in the downstream ends of open leads and
channels. FA-104 (Whiskers Slough) and FA-128 (Slough 8A) both were open. The main
channel of the Susitna was still ice covered at Slough 8A, although the ice cover had
deteriorated. Open leads upstream of 8A were wider, transitioning to extended sections of
open channel. Through Devils Canyon, the river was almost entirely open. Ice bridges had
collapsed and overall the channel had become wider. Above Devils Canyon there was a long
reach of open channel that extended farther upstream than the previous flight. Large ice
chunks were moving downstream. There was still continuous ice cover through the dam site,
but open leads and overflow had increased. There was an accumulation developing upstream
of the dam site.
April 30: The sloughs and side channels of the lower reaches of the Middle River were
completely open. Overflow overtopped the open channel in places which caused overflow
onto the ice surface of the main channel. Deteriorated ice covered the Chulitna confluence.
An open lead on along the right bank extended from the Chulitna confluence upstream to
FA-104, Whiskers Slough which was open. The slough at FA-115 was open but had not
breached the Susitna main channel. The main channel of the Susitna had open leads in FA-
128 and the channel was open immediately upstream. A long and wide lead was open along
the left bank at Gold Creek. Through lower Devils Canyon, the last remaining ice covered
section had collapsed. Accumulated ice chunks appeared to be from shear walls calving and
were clogging the channel. The upper portion of the lower canyon was completely open. The
upper canyon has one small ice bridge remaining but the rest of the canyon was open and
running fast. The channel above the canyon was open although shore fast ice remains along
the banks. Much of the border ice had broken off and had accumulated in the downstream
ends of open leads. The ice cover through the dam site was still intact but continued to
deteriorate with overflow flooding the thalweg channel.
May 2: The Middle River had shown significant signs of melting and breakup with many of the
sloughs and side channels opening up. There was more connectivity between open reaches
and the ice cover showed more signs of rotting. While there were open sections through FA-
104 (Whiskers Slough), this reach had very thick freeze-up jamming accumulations and the
ice had remained in place for longer than many reaches. FA-128 (Slough 8A) has significant
open water in the sloughs, with the open leads in the main channel becoming more
pronounced. Slough 8A, Upper Side Channel 8A, and Middle Side Channel 8A in FA-128
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were entirely open. Accumulations were forming at the upstream edges of the ice cover.
Above Portage Creek and through Devils Canyon the river presented wide open leads and
almost no ice covered sections remained. There were areas above Devils Canyon where little
ice remained, even along the shoreline. There was a short accumulation at the dam site that
extended from PRM 186.8 to 187.6.
May 5: The Middle River was primarily open with two significant ice accumulations and shear
walls in several locations. The larger accumulations at FA-104 and FA-128 were forcing ice
and water over banks and had inundated islands as shown in Figure 5.3-4. The accumulation
at Whiskers Slough appeared to be held back by intact ice cover which has not weakened
enough to move downstream. This was the same ice cover which was very thick from freeze
up jamming. It showed signs of continued melt but continued to hold. A similar situation
occurred at FA-128 with remnant ice holding back an accumulation upstream of the Focus
Area. All side channels were open except for Lower Side Channel 8A which had an intact ice
cover showing significant signs of melting and deterioration. Significant shear walls were
present at FA-104, FA-128, FA-138, near the confluences of Gold Creek, Indian River, and
Portage Creek, and just below the dam site.
May 8: The Middle River was open with shear walls in several locations. Water was now
passing through open channels in the large accumulation at FA-104. Large shear walls
upwards of 15 feet remained (Figure 5.3-5) but water levels had dropped and previously
inundated islands were now high and dry. There was a similar situation at FA-128. Shear
walls were present through the Focus Area, but the main channel and all side channels were
open except for Lower Side Channel 8A which had an intact ice cover continuing to show
significant signs of melting and deterioration.
5.3.2.1. Middle River Time-lapse Cameras
PRM 104.3, Whiskers Slough near FA-104: Snow covered the site and began melting with
ponding visible on April 17. Ponding increased in depth and by the end of the day on April
23, the ponding meltwater appeared to begin flowing. Overflow upstream of the site is
thought to have added to the flow observed. The flow over the ice cover eventually created
an open channel section which began to accumulate brash at the downstream end on April
28. The stage began to rise on May 2 and the open channel continued to grow in width yet by
the night of May 3 an ice accumulation covered the entire channel and did not move until
May 7. Between 18:00 and 20:00 May 7, the accumulation was flushed out with several
additional ice runs from upstream moving through the site. Only shorefast ice remained on
the morning of May 8.
PRM 113.2, Slough 6 near FA-113: Meltwater from the snow cover began visibly ponding on
the ice in the evening of April 19. The channel nearest to the right bank, farthest from the
camera, appeared to be open on the morning of April 20 as brash seemed to be accumulating.
Significant accumulation began in the far channel on April 24 and a stage rise was observed
on April 28 which caused overflow to cover most of the ice. The far bank accumulation
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flushed out leaving the channel open on May 1. By this point the near bank remnant ice cover
was showing increased stress fractures and signs of deterioration. The afternoon of May 2
brought a large ice run which flushed the remnant ice downstream but caused an
accumulation which held till the evening when the far channel flushed out. The channel was
open with remnant ice on shores and banks which was eventually carried downstream. The
channel was clear of ice by the afternoon of May 5.
PRM 115.4, Slough 6 near FA-115: Freeze up 2013 left the main channel ice cover jumbled and
collapsed at the thalweg. This depressed thalweg had meltwater from melting snow. Between
April 15 and 25, the depressed thalweg experienced cycles of flowing overflow and ponding
meltwater as temperatures fluctuated daily. By the evening of April 25, brash was observed
accumulating in the open channel and the next morning the accumulation released and the
open channel was flowing. The channel remained open until May 1 when a large ice run
from upstream filled the channel and remained in place, covering the channel with ice. The
following morning the remnant ice cover and brash accumulation showed signs of shifting
and the entire channel was ice free from a single large flush as of 19:00 on May 2. A second
smaller ice run accumulated in the channel in the morning of May 3, but by 10:00 the
accumulation had moved out of the site. All ice was free of the channel with ice left only
stranded on banks and bars by the end of the day May 3.
PRM 129.6, Slough 8A near FA-128: No images from this site were captured while the camera
was deployed. It is unknown what type of malfunction occurred.
PRM 132.2, Slough 9: Snow covered the channel and the first ponding meltwater was observed
on April 11. On April 12, the ponding water levels increased and flowing water was
observed. The flowing water continued until the final image for the site was taken on April
15 at 13:15. Malfunction is suspected for the camera as no images were captured following
April 15.
PRM 138.5, Slough 11 near FA-138: Snowmelt and ponding water was first observed on the
snow-covered ice on April 18. The first observed ice movement occurred on April 26 as a
brash accumulation began forming at the far right bank of the river. By April 30 the stage
began to rise and overflow was visible at the mid-channel. The gradual melt out of ice was
interrupted on May 3 when a large accumulation associated with high flow inundated the
site. The image captured at 15:45 on May 3 revealed that upwards of 5 feet of brash ice
accumulated at the site during a 15 minute time span. The accumulation began to wash out
within the next 30 minutes and the site experienced two more ice run events similar to this
before finally having all ice flushed from the site on May 7. Ice left stranded on the banks
and bars (out of the channel) continued to melt in place.
PRM 142.2, near Indian River and FA-141: This camera malfunctioned during the morning of
April 26. The camera continued to work beyond this day, but the timestamp was reset to
January 1, 2012 at 06:00. This could occur due to a loss of power. Based on the known time
that the camera was turned off on May 15, 2014 it was possible to detemine the actual timing
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of events recorded with timestamps that were in error. For this reason, the description
following April 26 does not match the dates on the time lapse recording.
The ice cover had snow over the entire channel and the open thermal lead nearest the camera,
on the right bank of the river, persisted as an open channel. Ponding water was first observed
on April 15 at the mid channel and the amount of water increased to cause water to flow over
the surface of the ice by April 18. Ice cover under the overflow deteriorated and an open
channel remained. The first brash accumulation occurred on April 25 and the channel was
completely filled by the early afternoon of the same day.
Over a period of two days, the stage increased and caused the weak ice cover to breakup and
begin moving downstream on April 30. Ice runs moved through and briefly stopped on May
2 but the channel totally cleared late on May 3. The water level increased with ice deposited
on the shore on May 5 about midday and a significant ice run passed by at 18:00. The
channel stayed open after this with only minor passages of brash ice.
PRM 145.7, Slough 21 near FA-144: Freeze up 2013 produced a very rough ice cover in this
section. Snow covered the area and the first meltwater ponding was observed on April 19.
The meltwater fluctuated in ponding depth until April 26 when a visible and sustained stage
rise occurred. The ice surface elevation was not affected by this stage rise and so it was
assumed that the flow observed was on the ice surface and not directly connected to main
channel flow. A second stage increase was observed on May 2 and both the surface flow and
ice surface elevations increased. Increased overflow on the ice surface was observed. During
the night of May 2 the ice cover broke up as the first image of the day on May 3 revealed ice
stranded on both banks but the main channel was ice free. Two additional ice runs passed the
site but no further flooding or accumulations formed. The main channel was clear of ice with
shorefast ice and sheerwalls upwards of 7 feet as of the evening of May 4.
5.3.3. Upper River Observations
April 14: Lower sections of the Upper River had significant signs of previous overflow but all
surface water appeared to be refrozen. The ice cover appeared solid and continuous for a
majority of this reach. Near the Oshetna confluence there were small open leads where the
main channel ice cover had collapsed but no significant open water sections were observed.
April 21: From the dam site upstream, the Upper River had signs of overflow corresponding to
the thalweg location. Open leads were present in Vee Canyon. The thalweg channel was
generally sunken although it remains intact. Open leads were more frequent and ice had
shown continued deterioration since the previous flight. There were short sections where
open leads with large ice chunks in the downstream ends had refrozen. Near the Oshetna
confluence, there were numerous small open leads and holes where the main channel ice
cover had collapsed. The confluence with the Oshetna River was not open.
April 23: There were sections of open water immediately above the dam site up to about PRM
190, then intermittent open leads up to PRM 200. Vee Canyon was primarily open with short
sections where ice remained intact. Where there was an intact ice cover, the thalweg channel
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was generally sunken with overflow on the ice surface as shown in Figure 5.3-6. Near the
Oshetna confluence there were numerous small open leads where the main channel ice cover
had collapsed. The confluence with the Oshetna River was not open but there were short
sections of the OshetnaRiver ice cover that were beginning to open.
April 25: Immediately above the dam site there were extended sections of open water that
generally were wider at the downstream ends and narrowed to thin open leads in their
upstream ends. Ice accumulations were often the only remaining interruption between the
open sections. Where the river remained ice covered, overflow in the thalweg channels had
increased to almost bankfull depth, and in places overflow spilled onto the remaining ice
surface. Vee Canyon was primarily open with short sections of intact ice. Near the Oshetna
River confluence, there were numerous sections of open channel connected with remnant ice
cover. Ice cover in the thalweg channel had collapsed with fast moving overflow running
down the channel. The confluence with the Oshetna was not yet open, but the main channel
of the Oshetna was a combination of open holes and collapsed channel.
April 28: Immediately above the dam site the open water sections were similar to the previous
flight with similar accumulations interrupting open sections. Where the river remained ice
covered, overflow in the thalweg channels had increased to bankfull depth and in places
spilled out onto the ice surface. Near the Oshetna confluence there were numerous sections
of open channels interrupted by remnant ice cover. Ice cover in the thalweg channel had
collapsed with fast moving overflow running down the channel. At the Oshetna confluence,
overflow was running into the main channel of the Susitna from the Oshetna and
accumulations were developing on the Oshetna.
April 30: Immediately above the dam site, the extended sections of open water identified on
April 28 were longer, wider, and more frequent. Ice accumulations were often the only
remaining interruption between the open sections. Where the river remained ice covered,
overflow in the thalweg channels was at bankfull depth. Vee Canyon was open; however, a
large accumulation of ice had developed mid-canyon. Nearing the Oshetna confluence there
were numerous sections of open channel separated by remnant ice cover. At the Oshetna
confluence, overflow was running into the main channel of the Susitna from the Oshetna
similar to the previous flight.
May 2: There were many sections of open water immediately above the dam site which
continued as intermittent open leads up to PRM 200. Where the cover was still intact, it was
showing significant signs of rotting with overflow and shorter open leads corresponding to
the thalweg. There was an accumulation downstream of Vee Canyon but the canyon itself
was open. Near the Oshetna confluence there was evidence of a recent jam and failure with
large ice chunks pushed onto both banks but below the vegetation line as shown in Figure
5.3-7. The confluence with the Oshetna was open.
May 5: Open water was dominant above the dam site to PRM 200, where an intermittent
remnant ice cover, showing significant deterioration and melting, began. The ice cover had
numerous open leads and open channels throughout and appeared to be shorefast on gravel
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bars. Several small accumulations were present above the remnant ice covers with the largest
accumulations present below the mouth of Kosina Creek and at PRM 222. The accumulation
at PRM 222 appears to be remnant debris from the accumulation at Vee Canyon (PRM 225)
observed on May 2. A significant shear wall was present through Vee Canyon. Near the
Oshetna confluence, the remnant evidence of a jam failure was still present.
May 8: Open water was dominant above the dam site to PRM 200 and remained similar to the
observations from the previous flight. The ice cover at PRM 200 was about a mile long and
held back a small accumulation. A larger ice cover was present from PRM 206-223. The ice
cover had numerous open leads and open channels throughout and appeared to be shorefast
on gravel bars. The confluence with the Oshetna was open.
5.3.3.1. Upper River Time-Lapse Cameras
No time-lapse cameras were installed in the Upper River during the 2013/2014 winter field
season due to ongoing negotiations regarding land access permits.
5.4. Meteorological Data Collection
NWS air temperature data collected at Talkeetna was at or above long term averages for the
2013/2014 winter with January being upwards of 17 degrees Fahrenheit warmer on average than
the long term records. Spring brought mild temperatures that stayed close to the long term
averages.
Snowpack and snow water equivalent were at or below long term averages as measured at Point
Mackenzie, Susitna Valley High School, and Tokositna Valley. Tokositna Valley snow water
equivalents were up to 3 inches less for the 2013/2014 season cumulative measurements than
cumulative long term averages. The low snowpack and snow water equivalent led to the low
observed discharge in the Susitna River during spring breakup. Details of meteorological data
can be found in Appendix A. Stage and temperature records at the ESS stations can be found in
Appendix B.
6. LITERATURE CITED
AEA (Alaska Energy Authority). 2011. Pre-Application Document (PAD): Susitna-Watana
Hydroelectric Project FERC Project No. 14241. Prepared for the Federal Energy
Regulatory Commission by the Alaska Energy Authority, Anchorage. December 2011.
AEA (Alaska Energy Authority). 2012. Revised Study Plan (RSP): Susitna-Watana
Hydroelectric Project FERC Project No. 14241. Prepared for the Federal Energy
Regulatory Commission by the Alaska Energy Authority, Anchorage. December 2012.
Michel, Bernard. 1971. Winter Regime of Rivers and Lakes. Cold Regions Research and
Engineering Laboratory.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 25 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
NOAA Satellite and Information Service. NNDC Climate Data Online. Talkeetna Airport
Weather Station. Site number 99999926528 and 70251026528.
http://www7.ncdc.noaa.gov/CDO/cdoselect.cmd?datasetabbv=GSOD&countryabbv=&ge
oregionabbv=. Accessed 6/1/2013.
USACE (U.S. Army Corps of Engineers). 2002. EM 1110-2-1612 Engineering and design, Ice
Engineering. Department of the Army. U.S. Army Corps of Engineers CECW-EH
Washington, D.C. 20314-1000.
USGS Surface Water Data Collection Program. Streamflow data for the Susitna Basin. http://
http://waterdata.usgs.gov/ak/nwis/dv/?site_no=15292000&agency_cd=USGS&
referred_module=sw. and http://
http://waterdata.usgs.gov/ak/nwis/dv/?site_no=15292780&agency_cd=USGS&
referred_module=sw. Accessed 5/12/2013.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 26 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
7. TABLES
Table 4.2-1. Time-Lapse Camera Information
Station/Location Project River Mile Condition
Alexander Slough near Upper Tidal Influence 13.9 Removed 5/8/2014
Susitna Station 29.8 Removed 5/8/2014
Rustic Wilderness, Side Channel 64.2 Removed 5/8/2014
Susitna Landing 65.2 Removed 5/8/2014
Birch Creek 91.7 Removed 5/8/2014
Whiskers Slough – FA-104 104.3 Removed 5/15/2014
Slough 6 – FA-113 113.2 Removed 5/15/2014
Slough 6A – FA-115 115.4 Removed 5/15/2014
Slough 8A – FA-128 129.6 Removed 5/15/2014
Slough 9 132.2 Removed 5/15/2014
Slough 11 – FA-138 138.5 Removed 5/15/2014
Indian River – FA-141 142.2 Removed 5/15/2014
Slough 21 – FA-144 145.7 Removed 5/15/2014
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 27 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
8. FIGURES
Figure 3.1-1.Map of Ice Processes Study Area
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 28 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Figure 4.2-1. Map of Time-Lapse Camera Locations and Pressure Transducers
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 29 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Figure 5.1 - 1. Susitna River at Tsusena Creek USGS Gage, #152917000. Note: 2012 Discharge was Maximum discharge
for period of record
Figure 5.1 - 2. Susitna River at Gold Creek USGS Gage, #15292400
0
2,000
4,000
6,000
8,000
10,000
12,000
14,000
16,000
18,000
20,000
Discharge (cfs) Date
Susitna River at Tsusena Creek Discharge
Max
Min
Mean
2012
2013
0
5000
10000
15000
20000
25000
30000
35000
40000
Discharge (cfs) Date
Susitna River at Gold Creek Discharge
Max
Min
Mean
2012
2013
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 30 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Figure 5.1 - 3. Susitna River at Sunshine USGS Gage, # 15292480
Figure 5.1 - 4. Average Monthly Temperatures at Talkeetna
0
10000
20000
30000
40000
50000
60000
70000
Discharge (cfs) Date
Susitna River at Sunshine Discharge
Max
Min
Mean
2012
2013
0
10
20
30
40
50
60
70
Oct Nov Dec Jan Feb Mar Apr May JunTemperature (F) Month
Average Monthly Temperatures at Talkeetna
PATK Historical PATK 2011/2012 PATK 2012/2013 PATK 2013/2014
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 31 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Figure 5.1 - 5. Ice Front Progression and Ice Bridge Locations – Freeze-up 2012
0
50
100
150
200
250
15-Oct 30-Oct 15-Nov 30-Nov 16-Dec 31-DecRiver Mile Observation Date
Freeze-up 2012 Ice Cover Progression
22-Oct 23-Oct 25-Oct 26-Oct
29-Oct 1-Nov 7-Nov 8-Nov
15-Nov 18-Nov 20-Nov 28-Nov
3-Dec 19-Dec Talkeetna River DS Devils Canyon
US Devils Canyon Dam Site
Talkeetna River
Dam Site
DS End Devils Canyon
US End Devils Canyon
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 32 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Figure 5.1 - 6. Ice Front Progression and Ice Bridge Locations – Freeze-up 2013
0
50
100
150
200
250
15-Oct 30-Oct 15-Nov 30-Nov 16-Dec 31-DecProject River Mile Observation Date
Freeze-up 2013 Ice Cover Progression
6-Nov 8-Nov 12-Nov 15-Nov
19-Nov 21-Nov 25-Nov 29-Nov
3-Dec 12-Dec 18-Dec 23-Dec
Talkeetna River DS Devils Canyon US Devils Canyon Dam Site
US End Devils Canyon
DS End Devils Canyon
Talkeetna River
Dam Site
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 33 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Figure 5.1 - 7. Ice bridge formed near the mouth of the Susitna river on November 12, 2013
Figure 5.1 - 8. Frazil ice moving through the Delta Islands area
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 34 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Figure 5.1 - 9.Heavy frazil and border ice growth on Middle River on Novermber 8, 2013
Figure 5.1 - 10. Anchor ice deposits on the bed on December 3, 2013
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 35 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Figure 5.1 - 11. Shear walls and frazil jams in Devils Canyon on December 18, 2013
Figure 5.1 - 12. Anchor ice and border ice growth on the Upper River on November 19, 2013
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 36 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Figure 5.2 - 1. Open velocity lead follwoign thalweg in Lower River on February 21, 2014
Figure 5.2 - 2. Open thermal lead following edge of island on February 21, 2014
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 37 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Figure 5.2 - 3. Thermal lead along right bank at FA-104 on February 21, 2014
Figure 5.2 - 4. Open velocity lead in the Upper River on February 20, 2014
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 38 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Figure 5.3 - 1. Downstream edge of ice cover in Lower River on April 28, 2014
Figure 5.3 - 2. Mouth of the Talkeetna river on April 28, 2014
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 39 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Figure 5.3 - 3. FA-128 showing Slough 8A open on April 25, 2014
Figure 5.3 - 4. Ice jam and overbank flooding upstream of FA-128 on May 5, 2014
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 40 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Figure 5.3 - 5. Shear walls upstream of FA-104 on May 8, 2014
Figure 5.3 - 6. Flooded ice surface at thalweg, Upper River on April 23, 2014
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 41 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Figure 5.3 - 7. Evidence of previous jam at mouth of the Oshetna River on May 2, 2014
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 42 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
APPENDIX A: METEOROLOGICAL DATA FOR THE SUSITNA BASIN
Appendix A-1 Talkeetna Weather Station Data Tables
Appendix A-2 Winter 2013/2014 Freezing Degree Days
Appendix A-3 Spring 2014 Thawing Degree Days
Appendix A-4 2013 Talkeetna Temperature Comparison
Appendix A-5 Susitna Basin SNOTEL Data
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 1 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Appendix A-1
Susitna Weather Station Data Tables
OCTOBER 2013
Date
PATK
Historical
Ave Temp (°F)
Near PRM100
PATK
2012
Ave Temp (°F)
Near PRM100
PATK
2013
Ave Temp
(°F) Near
PRM100
ESM1 Watana
Met Station
2013
Ave Temp (°F)
Near PRM186.5
ESM2
Cantwell Met
Station
2013
Ave Temp (°F)
ESM3 Gold
Creek Met
Station
2013
Ave Temp (°F)
Near PRM140
1-Oct 40 31 44 39
2-Oct 40 38 41 37
3-Oct 40 40 43 39 36 40
4-Oct 39 44 43 40 35 44
5-Oct 39 47 39 39 37 39
6-Oct 39 45 41 34 33 37
7-Oct 38 43 40 33 36 38
8-Oct 37 41 38 32 33 38
9-Oct 36 44 38 34 35 35
10-Oct 36 43 33 33 33 36
11-Oct 35 41 37 29 25 34
12-Oct 35 35 40 34 32 36
13-Oct 34 34 44 38 35 38
14-Oct 34 34 39 38 34 39
15-Oct 33 32 42 33 32 38
16-Oct 33 27 41 34 34 36
17-Oct 32 27 44 37 36 38
18-Oct 31 23 44 38 32 41
19-Oct 31 33 42 37 36 40
20-Oct 31 32 41 37 36 39
21-Oct 30 31 39 34 32 39
22-Oct 30 18 38 29 26 34
23-Oct 29 18 32 31 27 34
24-Oct 28 34 30 24 16 28
25-Oct 27 29 37 26 17 32
26-Oct 27 22 31 33 29 34
27-Oct 26 21 37 29 22 29
28-Oct 27 20 39 31 27 35
29-Oct 26 17 43 37 35 36
30-Oct 25 25 42 35 25 39
31-Oct 25 27 35 34 26 37
Highlight indicates an aerial reconnaissance or field event.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 2 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Appendix A-1
Susitna Weather Station Data Tables (continued)
NOVEMBER 2013
Date
PATK
Historical
Ave Temp (°F)
Near PRM100
PATK
2012
Ave Temp (°F)
Near PRM100
PATK
2013
Ave Temp
(°F) Near
PRM100
ESM1 Watana
Met Station
2013
Ave Temp (°F)
Near PRM186.5
ESM2
Cantwell Met
Station
2013
Ave Temp (°F)
ESM3 Gold
Creek Met
Station
2013
Ave Temp (°F)
Near PRM140
1-Nov 25 23 36 34 32 35
2-Nov 25 28 34 30 31 34
3-Nov 25 29 36 28 28 33
4-Nov 24 23 37 27 22 33
5-Nov 24 20 33 26 19 32
6-Nov 23 22 30 25 23 29
7-Nov 22 20 24 14 7 18
8-Nov 20 11 19 11 5 21
9-Nov 20 25 21 8 6 12
10-Nov 21 30 26 14 11 22
11-Nov 21 29 27 20 18 26
12-Nov 21 27 15 18 19 21
13-Nov 18 21 14 5 -6 4
14-Nov 17 25 21 12 10 17
15-Nov 18 26 21 18 17 20
16-Nov 18 26 14 13 4 19
17-Nov 17 20 -1 8 9 5
18-Nov 17 15 -1 2 -9 -5
19-Nov 16 16 -8 -5 -18 -8
20-Nov 17 13 -5 -14 -23 -10
21-Nov 17 8 2 -17 -28 -13
22-Nov 18 12 19 -7 -22 1
23-Nov 18 11 22 13 5 24
24-Nov 16 7 22 13 5 18
25-Nov 15 13 24 16 5 23
26-Nov 16 10 19 18 10 21
27-Nov 16 12 27 20 11 22
28-Nov 17 18 14 21 19 27
29-Nov 17 25 -14 3 4 4
30-Nov 13 28 -7 -4 -13 -13
Highlight indicates an aerial reconnaissance or field event.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 3 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Appendix A-1
Susitna Weather Station Data Tables (continued)
DECEMBER 2013
Date
PATK
Historical
Ave Temp (°F)
Near PRM100
PATK
2012
Ave Temp (°F)
Near PRM100
PATK
2013
Ave Temp
(°F) Near
PRM100
ESM1 Watana
Met Station
2013
Ave Temp (°F)
Near PRM186.5
ESM2
Cantwell Met
Station
2013
Ave Temp (°F)
ESM3 Gold
Creek Met
Station
2013
Ave Temp (°F)
Near PRM140
1-Dec 12 18 -2 -9 -23 -1
2-Dec 11 9 -2 -5 -21 -1
3-Dec 12 16 3 3 -15 0
4-Dec 11 6 11 8 0 7
5-Dec 12 -4 23 13 1 9
6-Dec 11 3 31 26 17 25
7-Dec 10 -6 34 25 22 32
8-Dec 12 10 33 26 25 32
9-Dec 14 21 30 26 21 30
10-Dec 14 26 27 17 12 25
11-Dec 14 25 26 13 11 22
12-Dec 16 23 15 5 -11 11
13-Dec 14 24 7 7 7 15
14-Dec 12 21 21 7 5 12
15-Dec 11 -4 12 10 7 17
16-Dec 12 5 -10 5 -3 4
17-Dec 11 -13 -19 -9 -18 -13
18-Dec 13 -3 -20 -14 -33 -19
19-Dec 16 2 12 -7 -30 -5
20-Dec 16 17 19 5 -8 14
21-Dec 13 14 25 8 -1 17
22-Dec 13 8 28 15 7 26
23-Dec 15 7 18 18 16 26
24-Dec 13 8 -8 2 -4 6
25-Dec 13 24 -8 -7 -33 -5
26-Dec 14 26 -10 -9 -37 2
27-Dec 12 28 -13 -13 -39 -4
28-Dec 12 17 17 -3 -32 4
29-Dec 13 32 21 9 -3 21
30-Dec 10 35 19 7 -2 13
31-Dec 11 32 16 7 -7 14
Highlight indicates an aerial reconnaissance or field event.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 4 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Appendix A-1
Susitna Weather Station Data Tables (continued)
JANUARY 2014
Date
PATK
Historical
Ave Temp (°F)
Near PRM100
PATK
2012
Ave Temp (°F)
Near PRM100
PATK
2013
Ave Temp
(°F) Near
PRM100
ESM1 Watana
Met Station
2013
Ave Temp (°F)
Near PRM186.5
ESM2
Cantwell Met
Station
2013
Ave Temp (°F)
ESM3 Gold
Creek Met
Station
2013
Ave Temp (°F)
Near PRM140
1-Jan 13 34 30 11 -4 23
2-Jan 13 30 29 19 9 28
3-Jan 12 32 28 19 10 24
4-Jan 11 31 29 19 10 26
5-Jan 13 29 32 20 10 26
6-Jan 11 33 34 24 18 31
7-Jan 10 29 32 24 12 28
8-Jan 9 17 27 17 18 24
9-Jan 9 8 28 19 16 22
10-Jan 9 19 24 18 14 23
11-Jan 11 24 18 10 2 17
12-Jan 11 27 8 -1 -2 5
13-Jan 12 32 12 0 -2 9
14-Jan 10 34 23 4 -10 13
15-Jan 10 31 27 18 9 24
16-Jan 12 20 30 20 3 27
17-Jan 12 16 34 23 16 30
18-Jan 12 9 35 34 26 34
19-Jan 13 14 33 29 21 32
20-Jan 14 25 34 23 9 29
21-Jan 13 25 35 27 5 28
22-Jan 14 26 36 30 14 33
23-Jan 12 29 37 32 19 33
24-Jan 9 27 39 35 32 35
25-Jan 9 21 39 34 36 34
26-Jan 11 3 37 35 30 37
27-Jan 12 -11 38 36 23 35
28-Jan 14 1 34 34 9 31
29-Jan 12 4 26 29 13 27
30-Jan 14 15 22 22 22 18
31-Jan 17 27 14 9 0 8
Highlight indicates an aerial reconnaissance or field event.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 5 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Appendix A-1
Susitna Weather Station Data Tables (continued)
FEBRUARY 2014
Date
PATK
Historical
Ave Temp (°F)
Near PRM100
PATK
2012
Ave Temp (°F)
Near PRM100
PATK
2013
Ave Temp
(°F) Near
PRM100
ESM1 Watana
Met Station
2013
Ave Temp (°F)
Near PRM186.5
ESM2
Cantwell Met
Station
2013
Ave Temp (°F)
ESM3 Gold
Creek Met
Station
2013
Ave Temp (°F)
Near PRM140
1-Feb 16 25 9 4 -10 3
2-Feb 14 27 10 9 -13 7
3-Feb 13 33 25 12 -12 20
4-Feb 12 31 24 14 -14 23
5-Feb 13 30 15 8 -14 18
6-Feb 17 23 7 1 -18 2
7-Feb 17 21 20 4 -13 7
8-Feb 17 24 19 6 -16 18
9-Feb 16 28 13 2 -21 11
10-Feb 16 33 17 -6 -26 7
11-Feb 18 30 6 -5 -29 8
12-Feb 17 18 1 -6 -29 2
13-Feb 16 25 3 -9 -21 4
14-Feb 16 29 12 -2 -13 6
15-Feb 16 31 20 5 -12 11
16-Feb 14 13 13 7 3 15
17-Feb 16 20 20 7 -8 12
18-Feb 17 23 17 7 -10 14
19-Feb 18 6 20 8 -7 15
20-Feb 16 20 12 8 -13 13
21-Feb 17 23 4 4 -9 -3
22-Feb 18 21 18 0 -17 1
23-Feb 18 19 23 8 -16 17
24-Feb 19 24 18 9 -16 21
25-Feb 20 26 17 7 -17 9
26-Feb 21 29 28 10 -14 12
27-Feb 21 29 38 22 -7 31
28-Feb 19 31 38 27 4 36
29-Feb 20 27
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Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 6 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Appendix A-1
Susitna Weather Station Data Tables (continued)
MARCH 2014
Date
PATK
Historical
Ave Temp (°F)
Near PRM100
PATK
2012
Ave Temp (°F)
Near PRM100
PATK
2013
Ave Temp
(°F) Near
PRM100
ESM1 Watana
Met Station
2013
Ave Temp (°F)
Near PRM186.5
ESM2
Cantwell Met
Station
2013
Ave Temp (°F)
ESM3 Gold
Creek Met
Station
2013
Ave Temp (°F)
Near PRM140
1-Mar 18 23 28 28 13 33
2-Mar 19 26 25 22 4 30
3-Mar 19 19 22 18 0 28
4-Mar 19 26 25 13 -2 20
5-Mar 20 29 25 14 7 22
6-Mar 21 23 20 17 10 24
7-Mar 21 32 10 14 7 13
8-Mar 22 31 19 8 -10 11
9-Mar 21 34 15 4 -13 17
10-Mar 21 33 20 3 -14 1
11-Mar 22 24 35 15 6 24
12-Mar 21 29 34 31 31 35
13-Mar 21 23 30 25 23 28
14-Mar 20 18 39 29 24 35
15-Mar 21 22 26 32 26 39
16-Mar 22 19 12 11 14 17
17-Mar 22 12 24 6 4 8
18-Mar 23 11 27 16 6 24
19-Mar 24 19 26 19 13 24
20-Mar 25 11 29 18 11 22
21-Mar 26 6 26 13 1 18
22-Mar 25 18 26 14 0 17
23-Mar 25 22 27 13 1 20
24-Mar 26 18 27 18 4 27
25-Mar 28 23 33 20 6 28
26-Mar 28 7 29 23 8 31
27-Mar 28 -2 27 21 7 24
28-Mar 28 15 23 16 5 20
29-Mar 27 28 23 15 4 20
30-Mar 28 32 24 15 5 20
31-Mar 28 35 26 17 7 21
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Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 7 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Appendix A-1
Susitna Weather Station Data Tables (continued)
APRIL 2014
Date
PATK
Historical
Ave Temp (°F)
Near PRM100
PATK
2012
Ave Temp (°F)
Near PRM100
PATK
2013
Ave Temp
(°F) Near
PRM100
ESM1 Watana
Met Station
2013
Ave Temp (°F)
Near PRM186.5
ESM2
Cantwell Met
Station
2013
Ave Temp (°F)
ESM3 Gold
Creek Met
Station
2013
Ave Temp (°F)
Near PRM140
1-Apr 29 30 29 17 9 21
2-Apr 30 28 26 18 11 23
3-Apr 31 34 26 19 10 21
4-Apr 31 31 32 17 10 22
5-Apr 31 27 36 21 14 29
6-Apr 32 19 37 24 19 34
7-Apr 32 21 36 28 27 33
8-Apr 33 14 30 26 22 32
9-Apr 33 19 22 15 18 23
10-Apr 32 8 22 8 9 16
11-Apr 32 8 25 10 3 20
12-Apr 33 15 31 15 8 23
13-Apr 33 23 34 21 16 28
14-Apr 34 24 37 30 27 34
15-Apr 34 29 36 29 27 37
16-Apr 35 27 39 32 32 32
17-Apr 35 29 39 33 35 37
18-Apr 36 31 41 33 32 37
19-Apr 36 33 39 34 34 38
20-Apr 36 35 43 34 32 38
21-Apr 37 32 44 38 33 40
22-Apr 38 33 41 36 34 38
23-Apr 38 37 40 35 34 38
24-Apr 38 39 40 35 36 39
25-Apr 39 36 41 36 36 38
26-Apr 40 31 42 33 35 36
27-Apr 40 34 43 37 34 40
28-Apr 41 32 44 37 34 41
29-Apr 41 32 42 38 37 40
30-Apr 41 34 45 40 39 41
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Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 8 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Appendix A-1
Susitna Weather Station Data Tables (continued)
MAY 2014
Date
PATK Historical
Ave Temp (°F)
Near PRM100
PATK
2012
Ave Temp (°F)
Near PRM100
PATK
2013
Ave Temp (°F)
Near PRM100
ESM1 Watana
Met Station
2013
Ave Temp (°F)
Near PRM186.5
ESM2
Cantwell Met
Station
2013
Ave Temp (°F)
ESM3 Gold
Creek Met
Station
2013
Ave Temp (°F)
Near PRM140
1-May 42 35 48 41 38 42
2-May 42 38 59 43 41 46
3-May 42 34 56 48 45 49
4-May 42 36 53 51 46 47
5-May 42 39 53 50 45 45
6-May 43 38 49 48 44 45
7-May 44 37 44 39 41 40
8-May 44 40 46 39 42 42
9-May 44 44 50 44 44 44
10-May 44 48 56 45 45 47
11-May 45 48 55 46 42 50
12-May 46 51 54 47 43 51
13-May 46 45 54 51 47 50
14-May 46 41 57 48 46 48
15-May 47 40 54 47 45 53
16-May 47 39 57 51 48 51
17-May 47 36 61 53 53 54
18-May 47 33 57 53 52 56
19-May 48 34 49 41 44 49
20-May 49 38 50 39 42 46
21-May 50 42 52 42 43 49
22-May 50 46 55 44 43 49
23-May 50 49 53 46 44 51
24-May 51 52 55 48 46 51
25-May 52 56 53 50 47 52
26-May 52 56 52 45 46 48
27-May 52 58 50 50 51 53
28-May 52 64 49 43 47 46
29-May 53 66 51 45 48 47
30-May 53 64 51 48 52 50
31-May 52 60 48 49 50 49
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Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 9 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Appendix A-2
Winter 2013/2014 Freezing Degree Days
Winter 2013 to Spring 2014 Cumulative Freezing Degree Days at Talkeetna compared to
previous two years and long-term average. Plot created from National Weather Service
data from Talkeetna Airport weather station.
0
500
1000
1500
2000
2500
3000
29-Aug 18-Oct 7-Dec 26-Jan 17-Mar 6-May 25-JunCumulative Freezing Degree Days Date
Cumulative Freezing Degree Days, Talkeetna
Historical Average FDD 2011/2012 FDD 2012/2013 FDD 2013/2014 FDD
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 10 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Appendix A-3
Spring 2014 Thawing Degree Days
Spring 2014 Cumulative Thawing Degree Days at Talkeetna compared to previous two
years and long-term average. Plot created from National Weather Service data from
Talkeetna Airport weather station.
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400
500
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700
800
900
1000
6-Apr 16-Apr 26-Apr 6-May 16-May 26-May 5-Jun 15-Jun 25-Jun 5-JulCumulative Thawing Degree Days Date
Thawing Degree Days, Talkeetna
Historical Average TDD 2011/2012 TDD 2012/2013 TDD 2013/2014 TDD
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 11 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Appendix A-4
Temperature Comparison
Winter 2013 to Spring 2014 temperature at Talkeetna compared to the previous year and
long-term average. Plot created from National Weather Service data from Talkeetna
Airport weather station.
Winter 2013 to Spring 2014 comparison of average monthly temperatures at Talkeetna
between the previous two years and long-term average. Plot created from National
Weather Service data from Talkeetna Airport weather station.
-25
-10
5
20
35
50
65
1-Oct 1-Nov 1-Dec 1-Jan 1-Feb 1-Mar 1-Apr 1-MayTemperature (Degrees Fahrenheit) Date
2013 Talkeetna Temperature Comparison
PATK Historical PATK 2012-2013 PATK 2013-2014 Freezing Point (32 Degrees F)
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40
50
60
70
Oct Nov Dec Jan Feb Mar Apr May JunTemperature (F) Month
Average Monthly Temperatures at Talkeetna
PATK Historical PATK 2011/2012 PATK 2012/2013 PATK 2013/2014
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 12 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Appendix A-5
Susitna Basin Snow Depth Measurements
Tokositna Valley SNOTEL Site Daily Measurements of Snow Depth and Snow Water
Equivalent, 2013-2014. Data collected by the NRCS.
Susitna Valley High SNOTEL Site Daily Measurements of Snow Depth and Snow Water
Equivalent, 2013-2014. Data collected by the NRCS.
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5
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35
40
45
1-Oct 1-Nov 1-Dec 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-JunDepth (Inches) Date
Tokositna Valley
Snow Water Equivalent
Snow Depth
Historic Snow Water
Equivalent
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5
10
15
20
25
30
35
40
45
1-Oct 1-Nov 1-Dec 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-JunDepth (Inches) Date
Susitna Valley High School
Snow Water Equivalent
Snow Depth
Historic Snow Water
Equivalent
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 13 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Appendix A-5
Susitna Basin Snow Depth Measurements (continued)
Point MacKenzie SNOTEL Site Daily Measurements of Snow Depth and Snow Water
Equivalent, 2013-2014. Data collected by the NRCS.
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5
10
15
20
25
30
35
40
45
1-Oct 1-Nov 1-Dec 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-JunDepth (Inches) Date
Point Mackenzie
Snow Water Equivalent
Snow Depth
Historic Snow Water
Equivalent
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 14 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
APPENDIX B: SUSITNA RIVER SURFACE WATER STATION DATA
Appendix B-1 Surface Water Stations (ESS Stations) Period of Record
Appendix B-2 Surface Water Temperature and Stream Stage during Freeze up 2013
Appendix B-3 Surface Water Temperatures and Stream Stage during Breakup 2014
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix B - Page 1 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Appendix B-1
Surface Water Stations (ESS Stations) Period of Record
Period of Record of all ESS stations in the Susitna River basin as deployed between June
2012 and January 2014. Data is sparse for several stations.
Jun-12Jul-12Aug-12Sep-12Oct-12Nov-12Dec-12Jan-13Feb-13Mar-13Apr-13May-13Jun-13Jul-13Aug-13Sep-13Oct-13Nov-13Dec-13Jan-14ESS70 PRM 187.2
ESS65 PRM 176.5
ESS60 PRM 168.1
ESS55 PRM 152.1
ESS50 PRM 124.1
ESS45 PRM 116.6
ESS40 PRM 107.2
ESS35 PRM 102.1
ESS 30 PRM 98.4
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix B - Page 2 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Appendix B-2
Surface Water Temperature (°F) and Preliminary Stream Stage
for the Susitna River during Freeze up 2013
PRM 15.8 – Flathorn Lake (ESS10)
PRM 17.7 – Susitna River near Dinglishna Hill (ESS15)
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46
1-Oct 1-Nov 1-Dec 1-Jan Water Height (Ft) Water Temperature (°F) Date
Water Temperature
Water Height
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1-Oct 1-Nov 1-Dec 1-Jan Water Height (Ft) Water Temperature (°F) Date
Water Temperature
Water Height
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix B - Page 3 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Appendix B-2
Surface Water Temperature (°F) and Preliminary Recorded Stream Stage
for the Susitna River Freeze up 2013 (Continued)
PRM 29.8, Susitna Station (ESS20)
PRM 98.4 – Twister Creek (ESS30)
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1-Oct 1-Nov 1-Dec 1-Jan Water Height (Ft) Water Temperature (°F) Date
Water Temperature
Water Height
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6
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32
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42
1-Oct 1-Nov 1-Dec 1-Jan Water Height (Ft) Water Temperature (°F) Date
Water Temperature
Water Height
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix B - Page 4 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Appendix B-2
Surface Water Temperature (°F) and Preliminary Recorded Stream Stage
for the Susitna River Freeze up 2013 (Continued)
PRM 101.8 – Chulitna River (ESS35). No Data; Sensors at the station malfunctioned
during the May 2013 breakup.
PRM 116.7, Downstream of Lane Creek near Slough 6A – FA-115 (ESS45).
PRM 124.2, Curry Slough (ESS50)
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1-Oct 1-Nov 1-Dec 1-Jan Water Height (Ft) Water Temperature (°F) Date
Water Temperature
Water Height
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1
2
3
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7
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42
1-Oct 1-Nov 1-Dec 1-Jan Water Height (Ft) Water Temperature (°F) Date
Water Temperature
Water Height
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix B - Page 5 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Appendix B-2
Surface Water Temperature (°F) and Preliminary Recorded Stream Stage
for the Susitna River Freeze up 2013 (Continued)
PRM 152.2, Portage Creek – FA-151 (ESS55). No Data; Sensors at the station
malfunctioned during the May 2013 breakup.
PRM 168.2, Devil Creek (ESS60). No Data; Sensors at the station malfunctioned during the
May 2013 breakup.
PRM 176.4, Fog Creek – FA-173 (ESS65). No Data; Sensors at the station malfunctioned
during the 2012 freeze up.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix B - Page 6 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Appendix B-3
Surface Water Temperature (°F) and Preliminary Recorded Stream Stage
for the Susitna River Breakup 2014
PRM 15.8 – Flathorn Lake (ESS10)
PRM 17.7 – Susitna River near Dinglishna Hill (ESS15)
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1-Mar 1-Apr 1-May 1-Jun Water Height (Ft) Water Temperature (°F) Date
ESS10 (Near Flathorn Lake)
Water Temperature
Water Height
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1-Mar 1-Apr 1-May 1-Jun Water Height (Ft) Water Temperature (°F) Date
ESS15 (Near Dinglishna Hill)
Water Temperature
Water Height
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix B - Page 7 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Appendix B-3
Surface Water Temperature (°F) and Preliminary Recorded Stream Stage
for the Susitna River Breakup 2014 (Continued)
PRM 29.8, Susitna Station (ESS20); Sensors malfunctioned in mid-December.
PRM 98.4 – Twister Creek (ESS30)
PRM 116.7, Downstream of Lane Creek near Slough 6A – FA-115 (ESS45): Sensors at the
station malfunctioned during the May 2013 breakup.
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50
1-Mar 1-Apr 1-May 1-Jun Water Height (Ft) Water Temperature (°F) Date
ESS30 (At Twister Creek)
Water Temperature
Water Height
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix B - Page 8 September 2014
TECHNICAL MEMORANDUM DETAILED ICE OBSERVATIONS OCTOBER 2013 – MAY 2014
Appendix B-3
Surface Water Temperature (°F) and Preliminary Recorded Stream Stage
for the Susitna River Breakup 2014 (Continued)
PRM 124.2, Curry Slough (ESS50): Water temperature sensor at the station malfunctioned
during the winter 2013; the water height sensor appears to have malfunctioned on May 3rd,
during breakup.
PRM 152.2, Portage Creek – FA-151 (ESS55): Sensors at the station malfunctioned during
the May 2013 breakup.
PRM 168.2, Devil Creek (ESS60): No data recorded past 11/4/2013.
PRM 176.4, Fog Creek –FA-173 (ESS65): Sensors at the station malfunctioned during the
May 2013 breakup.
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1-Mar 1-Apr 1-May 1-Jun Water Height (Ft) Water Temperature (°F) Date
ESS50 (At Curry)
Water Temperature
Water Height
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix B - Page 9 September 2014