January 9, 2013 Field Trip Report
Susitna-Watana Ice Processes Study
Date: January 9, 2013
Crew: Bill Spencer and Mark Doner (HDR Alaska); pilot Alicen Bishop (JayHawk Aviation)
Talkeetna Weather: variable overcast with sun and fog against the mountains, temperature
varied from 10 to14 degrees Fahrenheit (F), light winds.
Objectives: Aerial survey of ice on the Susitna River and Mouth to Oshetna River confluence.
Data Collected:
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Photos (JPEG) with GPS points
Georeferenced video
Ice observations with GPS points
Summary: Air temperature was approximately 14 degrees F at the mouth of the river and
dropped to about 4 degrees F at the Oshetna River. Snow cover remained low near the Susitna
River mouth with no sign of open water. Periodic open leads on the main channel and sloughs
began at PRM 21, increasing in frequency upstream from the mouth of the Yentna River to one
lead every 2 river miles. The large open lead at Susitna Station had closed since the previous
survey on December 3, 2012.
On the middle river there was up to 6 inches of snow cover. Open leads continued at the same
frequency as on the lower river, increasing upstream from the Gold Creek Bridge. Overflow was
present upstream of the bridge and Devil Canyon. The canyon remained open with a total of five
ice bridges. Upstream from the dam site there were long intermittently open sections as well as
small open leads at the confluence of most tributaries. The Oshetna River was frozen at the
mouth.
Flight Path: The observations began at the mouth of the Susitna River, following the river’s
right side of the wide, braided section of the river. The team landed in Talkeetna at 1105 hours
for fuel and to change the camera battery. After departing Talkeetna, the team headed up the
mainstem of the Susitna River to the mouth of the Oshetna River, and then turned around. The
team stopped in Talkeetna to refuel at 1410 hours, returning to Merrill Field by 1525 hours.
Lower River Observations
Mouth to Talkeetna: There was very little snow cover on the lower river, areas of wind-blown
dust near the mouth, with most areas nearer the mouth blown clear of snow. There was no sign of
recent open water on the lower river. Open leads in the main channel occurred at a frequency of
about one lead every 2 river miles. About one third of the mainstem leads had visible frazil ice.
There were numerous open leads in the sloughs–none with visible frazil ice. There were
scattered and infrequent areas of overflow on the mainstem with limited patches of overflow in
sloughs.
Susitna-Watana Hydroelectric Project
FERC Project No. 14241
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Alaska Energy Authority
Draft: August 8, 2013
FIELD TRIP REPORT
SUSITNA-WATANA ICE PROCESSES STUDY
Talkeetna and Chulitna Rivers: The Talkeetna and Chulitna Rivers were both intermittently open
upstream of their respective confluence with the Susitna River.
Middle River Observations
Talkeetna to Dam Site: Snow cover on the Middle River was still very low (estimated at less
than 6 inches) though less affected by wind than the Lower River. Open leads in the mainstem of
the Middle River occurred at approximately the same frequency as in the Lower River
(approximately one lead every 2 river miles) and increased as the river narrowed upstream from
the Gold Creek railroad bridge. There was no visible frazil ice in the open leads in this section of
the river. Numerous open leads existed in the sloughs, yet none with visible frazil ice. The
occurrence of overflow increased in this section of the river, with some sections of river open
and flowing over the ice. There were patches of hummocky, rough ice where slush jams froze
and had not been covered with overflow.
Many of the mainstem open leads had visible anchor ice, especially near the downstream end of
Devil Canyon. Devil Canyon was nearly ice-free with the exception of five ice bridges. There
were significant stretches of over-ice flow upstream of the canyon (Figure 2), including
submerged broken pan ice.
The number of sloughs in the upper part of this section of the river decreased due to the
narrowing of the channel, and there were only a few open leads visible.
Upper River Observations
Dam Site to Oshetna Confluence: Open leads persisted intermittently through this reach. Many
of the mainstem open leads had visible anchor ice, especially near the canyon upstream of
Watana Creek. There was no visible frazil ice.
Upstream of Watana Creek there was a long stretch of solid blue-ice overflow. Upstream of this
overflow were patches of very rough ice and an approximately 1000 meter section with pressure
ridge ice buildup on the right bank.
Small open leads were visible at the confluence of most of the small tributaries. Areas of ice
build-up due to groundwater seeps from the right bank were visible in the upper stretches of this
section of the river (Figure 4).
The Susitna River had intermittent open leads downstream of the Oshetna River confluence and
continued into the visible distance upstream of the confluence. The Oshetna River was frozen
over at the confluence.
Susitna-Watana Hydroelectric Project
FERC Project No. 14241
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Alaska Energy Authority
Draft: August 8, 2013
FIELD TRIP REPORT
SUSITNA-WATANA ICE PROCESSES STUDY
Representative Photographs
Figure 1. Snow cover on the Susitna River at the Alexander Creek confluence, PRM 14.
Figure 2. Extensive overflow upstream of Devil Canyon, PRM 160.1.
Susitna-Watana Hydroelectric Project
FERC Project No. 14241
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Alaska Energy Authority
Draft: August 8, 2013
FIELD TRIP REPORT
SUSITNA-WATANA ICE PROCESSES STUDY
Figure 3. Smooth ice upstream of Watana Creek, PRM 203.
Figure 4. Ice buildup from groundwater seeps, PRM 202.
Susitna-Watana Hydroelectric Project
FERC Project No. 14241
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Alaska Energy Authority
Draft: August 8, 2013
FIELD TRIP REPORT
SUSITNA-WATANA ICE PROCESSES STUDY
Figure 5. Anchor ice, PRM 217.
Susitna-Watana Hydroelectric Project
FERC Project No. 14241
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Alaska Energy Authority
Draft: August 8, 2013