2011 Assiniboine River Flood
| Date | April 2011 – June 2011 |
|---|---|
| Location | Manitoba |
| Deaths | 1 |
| Property damage | >$1 billion |
The 2011 Assiniboine River flood was caused by above average precipitation in Western Manitoba and Saskatchewan. This was a 1 in 300 year flood that affected much of Western Manitoba. The flooding in Manitoba was expected to mostly involve the 2011 Red River Flood but instead the more severe flooding was found on the Assiniboine in the west.
The 2011 flood really started in the fall of 2010 with several major rainfall events and generally wet conditions. Initially, it was predicted that the flood along the Assiniboine River would be similar to the flood of 1995. During the winter of 2010–2011 the Shellmouth Reservoir was emptied in preparation, to store water for the coming spring flood. With more and more precitpitation, the estimates on the flood were revised upwards.
The first major settlement to experience the floodwater was St. Lazare, Manitoba which was located near the confluence of the Assiniboine River and Qu'Appelle River. Dikes were built up to protect against the rising floodwater, but unfortunately some residences were not spared as their protective dikes were overwhelmed. The flood continued downstream, spilling over its banks and flooding campgrounds and fields in the flood plain. Brandon, Manitoba's second largest city, prepared well in advance of the anticipated flood building up both earthen dikes as well as sandbag/Hesco bastion dikes. After a heavy snowfall on April 29 and 30 over much of the Assiniboine River watershed the crest forecast for Brandon was revised upward well above the flood of 1976. The river peaked at about 36,700 cu ft/s (1,040 m3/s),60% higher than the previous highest recorded peak of 23,000 cu ft/s (650 m3/s) in 1923. The 2011 event is estimated to be a 1 in 300-year flood.
Shortly thereafter a state of emergency was declared in Brandon as well as other municipalities across Manitoba. Premier Greg Selinger requested from Prime Minister Stephen Harper troops from the Canadian military to help with the flood fighting efforts. The last time the military was called in to help fight a flood in Manitoba was the 1997 Red River Flood.
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