HomeMy WebLinkAboutTrip Report_Knutson Creek_May1_2018MEMORANDUM State of Alaska
Department of Fish and Game
Division of Habitat
TO: Ron Benkert DATE: May 7, 2018
Regional Supervisor
Central Region Office SUBJECT: Knutson Creek
HOBO Logger Retreival
May 1, 2018
FROM: Josh Brekken PHONE NO: (907) 267-2113
Habitat Biologist
On Tuesday, May 1, 2018, Jacob Cunha and I flew to Pedro Bay to retrieve HOBO temperature
loggers that were deployed into the stream substrate of Knutson Creek in November 2017. A
hydroelectric project on Knutson Creek has been proposed and is in the planning stages. The
temperature loggers should provide information regarding the winter low-flow conditions as well
as potential salmon spawning viability within the reach of stream proposed for water diversion as
part of the hydroelectric project.
We traveled to the site on Knutson Creek with four-wheelers and on foot. The logger deployment
site is located about 1.8 miles upstream from the mouth of the river where more than 20 sockeye
salmon were observed spawning during a project related fish survey and within the reach that
will be affected by the hydroelectric project. We arrived in Pedro Bay around 10:00 am and
during our site visit the air temperature was about 42ºF, the skies were overcast, there was no
wind, and the river level was approximately 65 cfs.
The deployment site is located at the outlet of a small canyon just downstream of a sharp bend in
the river where the channel is confined (59.817809ºN/154.117394ºW). The channel becomes
unconfined a short distance downstream from the site. The stream habitat at the deployment site
is pool with a cascade immediately upstream and a long riffle downstream. The channel is about
50 feet wide at this location and the profile is uniform with the thalweg in the middle of the
channel. The substrate at the site is a mix of gravel (40%), cobble (50%), and sand (10%). The
loggers were deployed in gravels between the thalweg and river-left streambank. Based on the
valley constriction and channel morphology, a high degree of hyporheic exchange is expected at
this location.
Seven data loggers were installed in the substrate and all 7 were visible and easily retrieved. The
loggers were about 30 cm into the substrate. During retrieval, water depths ranged from 18 to 58
cm over the loggers. The thalweg water depth at the outlet control of the pool where the loggers
were placed was 68 cm. Appropriate spawning gravels occupy about 42 square meters at this
location with water depths ranging from 15 to 75 cm over the gravels during our visit.
Knutson Creek Site Visit, May 1, 2018 2 May 7, 2018
Hobo Data Logger Water Depth (cm)
2 37
3 48
4 55
5 52
6 56
7 18
8 58
Table 1. Water depth over logger location during retrieval (May 1, 2018)
We traveled back to Pedro Bay where we awaited our return flight to Anchorage. We departed
around 3:15 pm and arrived in Anchorage around 5:45 pm.
The loggers were successfully downloaded with all 7 units recording temperatures for the
duration of deployment. Temperatures were recorded twice daily and ranged from a high of
37.702 °F in early November to a low of 31.842 °F in late January. Average temperatures logged
by each probe ranged from 33.206 °F to 33.558 °F. The data indicates that these gravels
remained wetted throughout the winter months.
Knutson Creek Site Visit, May 1, 2018 3 May 7, 2018
Figure 1. Knutson Creek Substrate Temperatures, November 7, 2017 to May 1, 2018.
31.5
32.5
33.5
34.5
35.5
36.5
37.5
38.5
11/8/2017 12/8/2017 1/8/2018 2/8/2018 3/8/2018 4/8/2018
Knutson Creek Substrate Temperature
Hobo_2 °F Hobo_3 °F Hobo_4 °F Hobo_5 °F Hobo_6 °F Hobo_7 °F Hobo_8 °F
Knutson Creek Site Visit, May 1, 2018 4 May 7, 2018
Photograph 1. Logger deployment site, upstream view, May 1, 2018.
Photograph 2. Logger deployment site, downstream view, May 1, 2018. Two loggers are visible
in gravels at center and bottom of picture.
Knutson Creek Site Visit, May 1, 2018 5 May 7, 2018
Photograph 5. Underwater view of logger system deployed in substrate, November 10, 2017.
Photograph 6. Underwater view of loggers in substrate, November 10, 2017.
Knutson Creek Site Visit, May 1, 2018 6 May 7, 2018
Photograph 7. Overview of deployment site with logger locations marked, November 10, 2017.
Email cc:
A. Ott, ADF&G
T. Elison, ADF&G
J. Dye, ADF&G
K. Harper, ADF&G
J. Cunha, ADF&G
J. Groves, PolarConsult
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6 8
3 5
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