May 25, 2013 Field Trip Report
Susitna-Watana Ice Processes Study
Date: May 25, 2013
Crew: Robin Beebee and Lynn Spencer (HDR Alaska); Alicen Bishop, pilot (Jayhawk Aviation)
Talkeetna Weather: Clear and sunny, temperatures varied from 42 to 69 degrees Fahrenheit
(F).
Objectives: Video river, observe breakup progress.
Data Collected:
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Photos (JPEG) with GPS points
Georeferenced video
Ice jams, ice bridges, open lead locations, some notable tributaries, and other noteworthy
locations marked with GPS points.
Summary: Ice and water movement was very dynamic with ice jams giving way and reforming
again downriver. Large ice floes dominated the river channel. The Susitna River was open from
tidewater to PRM 50. From PRM 50 to 70 there were numerous ice jams and some ice coverage
with water flooding islands. Upstream of PRM 75 the main channel was open, though some side
channels and sloughs were still closed. The Talkeetna River was open and the Chulitna River
was open 5 miles upstream from the confluence.
Whiskers Slough was becoming jammed and flooded by large ice floes. There were various ice
jams along the middle river up to Devil Canyon. Ice bridges remained at the mouth of Portage
Creek. Fast, turbulent flow in Devil Canyon was breaking apart ice from the Upper River and
leaving only slush and small chunks downstream. Ice was broken up and rapidly moving
downstream above Devil Canyon.
Ice was still present from the dam site to Kosina Creek but was broken and jumbled. A massive
ice jam extended several miles downstream of Vee Canyon.
Flight Path: The team departed Merrill at 0945 hours and flew directly to the Susitna River
(PRM 25 just below the Yentna confluence). They flew the Susitna main channel upstream to the
Oshetna River confluence, traversing up and down river to observe breakup in full action.
Lower River Observations
Mouth to the Deshka River: The Lower River was clear, except for shelf ice and some side
channel ice, from the mouth to about PRM 50 (upstream of Deshka Landing) (Figure 1). The
mainstem in the vicinity of Susitna Station was open. Numerous ice floes were drifting
downstream in the lower river. Several jet boats were observed dodging the ice floes downstream
of Deshka Landing.
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Deshka River to Talkeetna: Between PRM 50 and about PRM 75 there were numerous jams and
some intact ice. No significant flooding was observed – ice jams were diverting water into side
channels and flooding brush on islands (Figure 2). The Kashwitna River mouth was open but the
main channel of the Susitna was almost completely jammed with flowing ice near its confluence
(Figure 3).
From PRM 75 to Talkeetna the main channel was open except for shelf ice and floes. Some of
the side channels and sloughs were still ice covered. The channel was completely open at the
Sunshine Bridge (Figure 4). The Talkeetna River was open, high, and silty (Figure 5). The
Chulitna River was clear up to the bluffs, except shelf ice was still present; the ice jams have
broken up since May 23, 2013 (Figure 6).
Middle River Observations
Whiskers Slough: The intact ice around Whiskers Slough broke up early afternoon and jammed.
At 1700 hours, the jam extended several miles upstream. Ice floes were flooding and jamming in
Whiskers Slough, along with debris (Figure 7).
Long ice jams had formed at PRM113 (Figure 8), Curry Station (Figure 9), and around PRM
125. Islands were inundated (Figure 10) at the upstream ends of jams, but most of the water was
diverted into side channels and not going overbank. Ice bridges remain at the mouth of Portage
creek but it was open upstream (Figure 11).
Devil Canyon: Devil Canyon was open and running high and fast. Several small ice bridges were
still holding, backing up ice jams behind. Large ice floes from the upper river were moving down
through the canyon that entered in large ice pans and were demolished by the time they exited
downstream (Figure 12).
The remaining Middle River ice cover all the way to the Dam Site had broken up, rapidly
moving in large continuous floes downstream. Trees and debris from the bank were jammed in
along with the ice pans. Tsusena Creek was 20 percent open.
Upper River Observations
Dam Site to Kosina Creek: The Upper River tributaries were mostly open water with some
remaining shelf ice, while the main channel still had thick ice floes. Water levels were high and
very turbid. Remnants of ice jams remained around the Dam Site. The ice cover from the Dam
Site upstream to Kosina Creek was partially broken but still present (Figure 13). Watana Creek
was open but significant shelf ice remains. There was a small jam at the mouth of Kosina Creek,
otherwise it was open (Figure 14).
Kosina Creek to the Oshetna River: A massive jam extended several miles below Vee Canyon
and was piled up behind several miles of intact ice. The jam had taken out spruce trees, backing
up water to overbank. Vee Canyon was high and turbulent. The Upper River around the Oshetna
confluence had recently broken up, and the remains of a jam were piled on gravel bars
(Figure 15).
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Representative Photographs
Figure 1. Just below the Yentna River confluence, PRM 29.4.
Figure 2. Ice jams at the upper end of the Delta Islands, PRM 57.7.
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Figure 3. Ice jams on the Susitna River at the Kashwitna River confluence, PRM 63.8.
Figure 4. Some ice floes and open water at Sunshine Bridge, PRM 87.7.
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Figure 5. The mouth of the Talkeetna River, PRM 100.5.
Figure 6. The Chulitna River, 5 miles upstream of the confluence.
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Figure 7. Ice jams at Whiskers Slough, PRM 105.4.
Figure 8. A long ice jam, PRM 113.
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Figure 9. Ice jam at Curry Station, PRM 124.6.
Figure 10. Inundated islands, PRM 125.6.
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Figure 11. Snow bridges at the mouth of Portage Creek, PRM 152.3.
Figure 12. Ice bridge in Devil Canyon, PRM 165.
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Figure 13. Broken but extensive ice cover, PRM 196.8.
Figure 14. Small ice jam at the mouth of Kosina Creek, PRM 209.
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Figure 15. Oshetna River confluence, PRM 235.
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