August 31, 2010
Flood Conditions Update
Warnings and Watches
· The flood warning is continued for the Assiniboine River downstream of the Shellmouth Dam.
· The flood watch is ended for the Interlake region, and the Swan River, Neepawa and Red Deer Lake areas.
Weather and Effect on Rivers and Lakes
· Unstable weather produced between 20 and 50 millimetres (0.8 and two inches) over fairly widespread portions of the Saskatchewan-Manitoba border and in southern and central Manitoba in the last 24 hours.
· Heavier storms were isolated and produced rainfall between 50 and 100 mm (two and four in.) in some regions including the Morris area.
· Some parts of Winnipeg received 50 mm (two in.). Fisher Branch and Riverton in the Interlake region both received 30 mm (1.2 in.).
· The forecast calls for a chance of rain showers of up to 15 mm (0.6 in) between today and tomorrow for portions of southern and central Manitoba.
· Significant rainfall up to 60 mm (2.4 in.) is expected in north central and northeast Manitoba including Gillam, Norway House, Wabowden and Cross Lake later this afternoon. However, no significant flooding is expected from this rainfall.
· Changes in river levels are not expected to be significant as heavier storms were isolated. However, if additional intense storms develop in the next few days, levels could change.
· The Red River at James Avenue rose by nearly 0.3 metres (one foot) because of localized overland flooding since yesterday. Overland flooding in Winnipeg occurred in isolated areas and a few incidents of sewer backup were reported this morning. The Red River was at 2.25 m (7.38 ft.) this morning at James Avenue.
· Localized overland flooding as well as basement flooding due to sewer backup or overwhelmed weeping-tile systems has been reported in the Morris area especially in the northwest part of the town. Significant overland flooding affected many area roads including PTH 75 and some farmland has been flooded.
· Due to the widespread nature of the rainfall, many streams in southern and central Manitoba including Assiniboine and Red River tributaries have experienced water level rises of up to 0.3 m (one foot).
· In the Interlake region, the Fisher, Icelandic and Bloodvein rivers are experiencing minor rises due to the rainfall in those areas. These streams will crest in the next two days unless additional heavy rain occurs. The Bloodvein River east of Lake Winnipeg has also experienced a minor rise.
· With favourable weather, the river flows are generally expected to stay well within their banks in southern and central Manitoba and are expected to crest between today and tomorrow if they have not already crested.
Assiniboine River and Shellmouth Reservoir Operation
· The Shellmouth Reservoir level has risen by three centimetres (1.2 in.) in the last 24 hours and stood at 429.9 m (1,410.43 ft.) this morning. The conduit was shut off this morning. The spillway flow is 1,700 cubic feet per second (cfs). The computed inflow is 2,500 cfs. The conduit will remain closed until the reservoir ouflow declines to 1,600 cfs.
· The Assiniboine River level immediately downstream of the reservoir is slightly above bank-full level. Additional heavy rain will cause river overbank flows leading to localized flooding affecting mainly low-lying areas. Upstream of the Shellmouth Reservoir, the Shell River and the Assiniboine River at Kamsack were rising as of this morning which will increase inflows into the reservoir.
Graphical information on lakes levels is updated regularly and posted at www.gov.mb.ca/waterstewardship/floodinfo/levels_flows.html.
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