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In western Canada, 15 of the 90 WSC hydrometric stations had at least one mid-winter break-up event between 1950 and 2008, and many of these rivers experienced multiple events. Additionally, six mid-winter break-up events were found in Alaska between 1950 and 2015. A total of 52 mid-winter break-up events occurred over the study period and are summarized in Table 1. The sizes of the drainage basins vary considerably, and there does not seem to be any discernable pattern between basin size, frequency, or timing of events.

Table 1

Summary of mid-winter break-up events by Water Survey of Canada station (Canada) or location of ice jam (Alaska)

River nameStation IDaLatitude (°)Longitude (°)Drainage area (km2)Number of eventsDates of break-upb
Canada 
 Athabasca River 07AE001 54.21 −116.06 19,600 12 Feb 1971, 21 Jan 1975 
 Blindman River 05CC001 52.35 −113.79 1,796 29 Jan 1998, 10 Mar 2005 
 Chilcotin River 08MB005 51.85 −122.65 19,200 14 Feb 1979, 3 Feb 2005 
 Coldwater River 08LG048 49.86 −120.91 316 13 24 Dec 1969, 21 Jan 1976, 26 Dec 1980, 20 Jan 1986, 11 Jan 1987, 25 Jan 1989, 28 Jan 1993, 5 Jan 1994, 31 Jan 1995, 4 Feb 1996, 28 Jan 2002, 24 Jan 2003, 24 Dec 2005 
 Elbow River 05BJ004 50.95 −114.57 791 16 Jan 1981 
 Fraser River 08KB001 54.01 −122.62 32,400 5 Jan 1962, 2 Mar 1963 
 Klondike River 09EA003 64.04 −139.41 7,810 15 Dec 2002 
 Little Smoky River 07GH002 55.46 −117.16 11,100 26 Feb, 1992 
 Oldman River 05AA023 49.81 −114.18 1,446 7 Mar 1979, 1 Jan 2000, 20 Jan 2005 
 Quesnel River 08KH006 52.84 −122.22 11,500 11 Jan 1971, 11 Feb 1982, 14 Jan 2007, 30 Jan 2008 
 Similkameen River (Hedley) 08NL038 49.38 −120.15 5,580 17 Jan 2001, 26 Dec 2005, 20 Jan 2007 
 Similkameen River (Princeton) 08NL007 49.46 −120.50 1,810 7 Jan 1970, 23 Jan 1987, 3 Jan 2007 
 Smoky River 07GJ001 55.72 −117.62 50,300 3 Dec 1956, 4 Jan 1958 
 Stikine River 08CF001 57.49 −131.75 36,000 24 Feb 1992 
 Wapiti River 07GE001 55.07 −118.80 11,300 26 Jan 1968, 2 Mar 1986, 29 Feb 1992, 16 Mar 1996, 12 Dec 1998, 5 Mar 2005 
Alaska 
 Kuskokwim River (Aniak) 15304000 + 61.59 −159.55 80,549b 13 Nov 2014 
 Kuskokwim River (Bethel) 15304300 60.79 −161.75 129,500 26 Nov 2010 
 Naknek River 15297890 58.69 −156.66 6,806 1 Mar 1963 
 Nushagak River 15302500 59.35 −157.47 25,486 19 Nov 2003 
 Tanana River 15481000 64.45 −147.07 44,651 19 Nov 2002 
 Wasilla Creek 15285000 61.64 −149.20 49 31 Dec 2010 
River nameStation IDaLatitude (°)Longitude (°)Drainage area (km2)Number of eventsDates of break-upb
Canada 
 Athabasca River 07AE001 54.21 −116.06 19,600 12 Feb 1971, 21 Jan 1975 
 Blindman River 05CC001 52.35 −113.79 1,796 29 Jan 1998, 10 Mar 2005 
 Chilcotin River 08MB005 51.85 −122.65 19,200 14 Feb 1979, 3 Feb 2005 
 Coldwater River 08LG048 49.86 −120.91 316 13 24 Dec 1969, 21 Jan 1976, 26 Dec 1980, 20 Jan 1986, 11 Jan 1987, 25 Jan 1989, 28 Jan 1993, 5 Jan 1994, 31 Jan 1995, 4 Feb 1996, 28 Jan 2002, 24 Jan 2003, 24 Dec 2005 
 Elbow River 05BJ004 50.95 −114.57 791 16 Jan 1981 
 Fraser River 08KB001 54.01 −122.62 32,400 5 Jan 1962, 2 Mar 1963 
 Klondike River 09EA003 64.04 −139.41 7,810 15 Dec 2002 
 Little Smoky River 07GH002 55.46 −117.16 11,100 26 Feb, 1992 
 Oldman River 05AA023 49.81 −114.18 1,446 7 Mar 1979, 1 Jan 2000, 20 Jan 2005 
 Quesnel River 08KH006 52.84 −122.22 11,500 11 Jan 1971, 11 Feb 1982, 14 Jan 2007, 30 Jan 2008 
 Similkameen River (Hedley) 08NL038 49.38 −120.15 5,580 17 Jan 2001, 26 Dec 2005, 20 Jan 2007 
 Similkameen River (Princeton) 08NL007 49.46 −120.50 1,810 7 Jan 1970, 23 Jan 1987, 3 Jan 2007 
 Smoky River 07GJ001 55.72 −117.62 50,300 3 Dec 1956, 4 Jan 1958 
 Stikine River 08CF001 57.49 −131.75 36,000 24 Feb 1992 
 Wapiti River 07GE001 55.07 −118.80 11,300 26 Jan 1968, 2 Mar 1986, 29 Feb 1992, 16 Mar 1996, 12 Dec 1998, 5 Mar 2005 
Alaska 
 Kuskokwim River (Aniak) 15304000 + 61.59 −159.55 80,549b 13 Nov 2014 
 Kuskokwim River (Bethel) 15304300 60.79 −161.75 129,500 26 Nov 2010 
 Naknek River 15297890 58.69 −156.66 6,806 1 Mar 1963 
 Nushagak River 15302500 59.35 −157.47 25,486 19 Nov 2003 
 Tanana River 15481000 64.45 −147.07 44,651 19 Nov 2002 
 Wasilla Creek 15285000 61.64 −149.20 49 31 Dec 2010 

aMWB date is the date of break-up initiation or the date of peak flow in the cases where initiation date was unavailable. For Alaska data, MWB is given as the date listed in the CRREL database.

bStation ID and estimated area from Crooked Creek.

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