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.
Summary of mid-winter break-up events by Water Survey of Canada station (Canada) or location of ice jam (Alaska)
| River name . | Station IDa . | Latitude (°) . | Longitude (°) . | Drainage area (km2) . | Number of events . | Dates of break-upb . |
|---|---|---|---|---|---|---|
| Canada | ||||||
| Athabasca River | 07AE001 | 54.21 | −116.06 | 19,600 | 2 | 12 Feb 1971, 21 Jan 1975 |
| Blindman River | 05CC001 | 52.35 | −113.79 | 1,796 | 2 | 29 Jan 1998, 10 Mar 2005 |
| Chilcotin River | 08MB005 | 51.85 | −122.65 | 19,200 | 2 | 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 | 1 | 16 Jan 1981 |
| Fraser River | 08KB001 | 54.01 | −122.62 | 32,400 | 2 | 5 Jan 1962, 2 Mar 1963 |
| Klondike River | 09EA003 | 64.04 | −139.41 | 7,810 | 1 | 15 Dec 2002 |
| Little Smoky River | 07GH002 | 55.46 | −117.16 | 11,100 | 1 | 26 Feb, 1992 |
| Oldman River | 05AA023 | 49.81 | −114.18 | 1,446 | 3 | 7 Mar 1979, 1 Jan 2000, 20 Jan 2005 |
| Quesnel River | 08KH006 | 52.84 | −122.22 | 11,500 | 4 | 11 Jan 1971, 11 Feb 1982, 14 Jan 2007, 30 Jan 2008 |
| Similkameen River (Hedley) | 08NL038 | 49.38 | −120.15 | 5,580 | 3 | 17 Jan 2001, 26 Dec 2005, 20 Jan 2007 |
| Similkameen River (Princeton) | 08NL007 | 49.46 | −120.50 | 1,810 | 3 | 7 Jan 1970, 23 Jan 1987, 3 Jan 2007 |
| Smoky River | 07GJ001 | 55.72 | −117.62 | 50,300 | 2 | 3 Dec 1956, 4 Jan 1958 |
| Stikine River | 08CF001 | 57.49 | −131.75 | 36,000 | 1 | 24 Feb 1992 |
| Wapiti River | 07GE001 | 55.07 | −118.80 | 11,300 | 6 | 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 | 1 | 13 Nov 2014 |
| Kuskokwim River (Bethel) | 15304300 | 60.79 | −161.75 | 129,500 | 1 | 26 Nov 2010 |
| Naknek River | 15297890 | 58.69 | −156.66 | 6,806 | 1 | 1 Mar 1963 |
| Nushagak River | 15302500 | 59.35 | −157.47 | 25,486 | 1 | 19 Nov 2003 |
| Tanana River | 15481000 | 64.45 | −147.07 | 44,651 | 1 | 19 Nov 2002 |
| Wasilla Creek | 15285000 | 61.64 | −149.20 | 49 | 1 | 31 Dec 2010 |
| River name . | Station IDa . | Latitude (°) . | Longitude (°) . | Drainage area (km2) . | Number of events . | Dates of break-upb . |
|---|---|---|---|---|---|---|
| Canada | ||||||
| Athabasca River | 07AE001 | 54.21 | −116.06 | 19,600 | 2 | 12 Feb 1971, 21 Jan 1975 |
| Blindman River | 05CC001 | 52.35 | −113.79 | 1,796 | 2 | 29 Jan 1998, 10 Mar 2005 |
| Chilcotin River | 08MB005 | 51.85 | −122.65 | 19,200 | 2 | 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 | 1 | 16 Jan 1981 |
| Fraser River | 08KB001 | 54.01 | −122.62 | 32,400 | 2 | 5 Jan 1962, 2 Mar 1963 |
| Klondike River | 09EA003 | 64.04 | −139.41 | 7,810 | 1 | 15 Dec 2002 |
| Little Smoky River | 07GH002 | 55.46 | −117.16 | 11,100 | 1 | 26 Feb, 1992 |
| Oldman River | 05AA023 | 49.81 | −114.18 | 1,446 | 3 | 7 Mar 1979, 1 Jan 2000, 20 Jan 2005 |
| Quesnel River | 08KH006 | 52.84 | −122.22 | 11,500 | 4 | 11 Jan 1971, 11 Feb 1982, 14 Jan 2007, 30 Jan 2008 |
| Similkameen River (Hedley) | 08NL038 | 49.38 | −120.15 | 5,580 | 3 | 17 Jan 2001, 26 Dec 2005, 20 Jan 2007 |
| Similkameen River (Princeton) | 08NL007 | 49.46 | −120.50 | 1,810 | 3 | 7 Jan 1970, 23 Jan 1987, 3 Jan 2007 |
| Smoky River | 07GJ001 | 55.72 | −117.62 | 50,300 | 2 | 3 Dec 1956, 4 Jan 1958 |
| Stikine River | 08CF001 | 57.49 | −131.75 | 36,000 | 1 | 24 Feb 1992 |
| Wapiti River | 07GE001 | 55.07 | −118.80 | 11,300 | 6 | 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 | 1 | 13 Nov 2014 |
| Kuskokwim River (Bethel) | 15304300 | 60.79 | −161.75 | 129,500 | 1 | 26 Nov 2010 |
| Naknek River | 15297890 | 58.69 | −156.66 | 6,806 | 1 | 1 Mar 1963 |
| Nushagak River | 15302500 | 59.35 | −157.47 | 25,486 | 1 | 19 Nov 2003 |
| Tanana River | 15481000 | 64.45 | −147.07 | 44,651 | 1 | 19 Nov 2002 |
| Wasilla Creek | 15285000 | 61.64 | −149.20 | 49 | 1 | 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.