November 28, 2012 Field Trip Report
Susitna-Watana Ice Processes Study
Date: November 28, 2012
Crew: Robin Beebee, Erin Cunningham (HDR Alaska); pilot Alicen Bishop (JayHawk Aviation)
Talkeetna Weather: Sunny, clear, 28 degrees high and 1 degree low Fahrenheit (F), winds NNE
at less than 10 mph.
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 jams, ice bridges, open lead locations, some notable tributaries and other noteworthy
locations marked with GPS points
Summary: The Susitna River from the mouth to PRM 16 was ice covered with no open leads.
Upstream the discontinuous open leads present on the November 20, 2012 flight in the main
channel, side channels, and side sloughs have continued to freeze over but many were still open.
Open leads at Susitna Station, the mouths of the Deshka and Yentna rivers, and in the main
channel from Birch Creek Slough to Talkeetna remain open. Frazil ice was visible in most open
leads.
The Middle River had discontinuous open leads in the ice cover, with frazil ice flowing and
anchor ice visible in most leads. Slough mouths were ice covered. A long open lead extended
from PRM 119 to PRM 124. Consistent ice cover ended at PRM 134 with open water extending
to PRM 153. The mouth of Portage Creek remained open but became ice covered upstream.
Periodic ice bridges began just downstream of Devil Canyon and continued up through the dam
site. The mouths of most sloughs and tributaries were frozen.
In the Upper River, ice cover started upstream of Dead Man Creek. There was thick and jumbled
ice upstream of Watana Creek and at the mouth of Kosina Creek. There may have been a blownout ice jam at the mouth of Kosina Creek. The upstream end of ice cover was still several miles
downstream of ESS80.
Flight Path: The team departed Merrill Field at 0945 hours and landed at the mouth of the
Susitna River to set up the video camera. The team then flew up the Lower Susitna River in
larger channels, landed in Talkeetna for fuel and to reset the camera. From there, the team flew
from the airstrip to the Talkeetna River, down to the Chulitna confluence, then up to the Indian
River confluence. The video camera appeared to have failed sometime during that flight. The
team landed to reset the camera, then flew to the Oshetna confluence, with a small side trip up
Kosina Creek to look at an apparent blown-out ice jam. They then returned to the Indian River
confluence, reset the camera, and flew the Middle River back down to Talkeetna with the video
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running. The helicopter was refueled in Talkeetna and the team returned to Merrill Field at 1540
hours.
Lower River Observations:
Mouth to Yentna Confluence: The lower portion of the Susitna River was ice-covered with no
open leads from the mouth upstream (Figure 1, Figure 2) to PRM 16, where an open lead was
present on the west bank of the Susitna River. The open lead in the front of Susitna Station was
still partially open (Figure 3).
Yentna River: An open lead was observed at PRM 33 (Figure 4), although it was much smaller
compared to the previous survey (November 20, 2012).
Yentna to Sunshine Bridge: Snowmachine tracks were visible between Flathorn Lake and
Susitna Station, crossing downstream from the open lead, and continuing on up Yentna River.
Kroto Slough was still ice covered. There was an open lead at the mouth of the Deshka River
with visible frazil ice (Figure 5). At PRM 53 there was an open lead in a side channel along the
right bank (Figure 6). There were discontinuous open leads from the mouth of Deshka upstream
through Delta Islands (Figure 7), then from Sheep Creek Slough until PRM 86 downstream of
Sunshine Bridge. Frazil ice was visible in most open leads, especially longer ones. Birch Creek
slough was ice covered.
Sunshine Bridge to Talkeetna: A mostly continuous open lead existed on the Susitna River from
Birch Creek up to Talkeetna (Figure 8). There was frazil ice flowing in an open lead, and several
anchor ice accumulations in the open lead large enough to produce rapids just downstream of
Talkeetna. Near Talkeetna, water and ice levels appeared to have dropped from near top of bank
to several feet lower based on observations of stranded ice on the banks.
Talkeetna and Chulitna Rivers: Talkeetna River still had open leads, but was freezing over by
shelf ice and anchor ice accumulation; frazil ice was flowing in the river. Chulitna River was still
ice covered, similar to the previous survey (November 20, 2012).
Middle River Observations:
Chulitna River to Gold Creek Bridge: Upstream of the confluence, the Susitna River was largely
ice covered. Whiskers Slough was predominantly ice covered, but had a few open leads on its
upstream end. An open lead at PRM 108 had some flow and ice was still visible (Figure 9). The
mouth of both Chase Creek and a slough at PRM 112 were frozen over. There were several
discontinuous leads between PRM 112 and a frozen-over slough at PRM 116.
Ice cover ended at PRM 119, and an open reach extended about 5 miles up to the bottom of
another ice bridge at PRM 124 (Figure 10). The upper edge of ice cover was associated with
significant over-bank flow and overflow into sloughs (Figure 11). Upper ice cover ended at PRM
134, upstream of Sherman and downstream of Gold Creek Bridge (Figure 12).
Gold Creek Bridge to Portage Creek: Upstream from Gold Creek Bridge the main channel
remained open but more anchor ice was visible in the main channel. Portage Creek was mostly
ice covered with a small open lead visible at the confluence with the Susitna River.
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Portage Creek to Devil Creek: Ice bridges and ice cover in Devil Canyon were similar to the
November 20, 2012 survey (Figure 13). Upstream from Devil Canyon the river remained largely
open with periodic ice bridges (Figure 14). A long ice bridge extended from PRM 163 to PRM
164.2.
Devil Creek to Dam Site: Mostly open water extended up to a series of ice bridges beginning at
PRM 183. Devil, Fog, and Tsusena Creeks were ice covered, with no open leads visible at the
mouth (Figure 15).
Upper River Observations:
Dam Site to Kosina Creek: Ice cover began upstream of Deadman Creek. The cover appears to
have jammed and blown out, as there was a substantial open lead with rubble ice in the channel
around it and overflow ice on the gravel bars. Upstream of Watana Creek there was especially
thick, hummocky ice occupying the channel from vegetated bank to vegetated bank. Brownish
hummocky ice on top of white hummocky ice appeared at the mouth of Kosina Creek; it
appeared that an ice dam on Kosina Creek blew out (Figure 16).
Kosina Creek to Oshetna River: Jay Creek was frozen over. The upstream end of ice cover was
still several miles downstream of ESS80. Goose Creek was mostly frozen, but the Oshetna was
mostly open.
Representative Photographs:
Figure 1. Ice cover on the lower Susitna River, PRM 3.
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Figure 2. Thin snow cover over ice, PRM 19.
Figure 3. Large open lead at Susitna Station still open from November 20, 2012, PRM 30.
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Figure 4. Open leads upstream of the Yentna confluence, PRM 34.7.
Figure 5. Ice cover on the Deshka River with open lead upstream of the mouth, PRM 45.
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Figure 6. Approximately 3-mile-long open lead in a side channel, PRM 53.
Figure 7. Large open lead, PRM 46.3 to 47.3.
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Figure 8. Open lead extending from PRM 91 up to Talkeetna.
Figure 9. A discontinuous open lead, PRM 108.
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Figure 10. Downstream end of a long open lead, from PRM 119.5 to 124.
Figure 11. Large open lead at the downstream end of Slough 8A, PRM 128.
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Figure 12. Upper end of extensive ice cover; lots of overflow onto banks and side channels, PRM 135.5.
Figure 13. Ice bridges in Devil Canyon, PRM 154.
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Figure 14. Open water downstream of Chinook Creek, PRM 158.6.
Figure 15. Frozen mouth of Tsusena Creek, PRM 184.6.
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Figure 16. Thick and jumbled ice at the mouth of Kosina Creek; possibly the result of a blown-out ice dam, PRM 209.
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