May 30, 2010
Flooding Update
Flood Advisory
An advisory for serious overland flooding is in effect for areas of southern Manitoba which have experienced unusually heavy rainfall for the past two days. Watersheds particularly hard hit include the La Salle, northern Morris, Sturgeon Creek, Seine River, Roseau River, Assiniboine River from Virden to Winnipeg. Many of these areas received 75 to 100 mm (2.9 to 3.9 inches) of rain during the past two days (May 28 to 29). Heavy rain also fell in portions of the Interlake and in the Whitemud River watershed and in the northern Whiteshell and Nopiming provincial parks.
Flood Conditions
Extensive overland flooding is underway in many areas of southern Manitoba due to recent heavy rains falling on soils already saturated from two storms on the Victoria Day long weekend. Streams have risen very rapidly due to Saturday’s downpours and some are overflowing their banks. Streams experiencing over-bank flows in low-lying areas include the La Salle River, northern portions of the Morris River, Sturgeon Creek, Roseau River tributaries and portions of the Seine River. Most of these streams are still rising but should crest during the next few days.
Major Streams
Levels of the Red and the Assiniboine rivers had been rising from previous rains and have risen more rapidly due to Saturday’s downpours. The Red River from Emerson to the floodway inlet has risen about 1.2 metres (four feet) since yesterday and 2.1 to 2.4 m (seven to eight ft.) in some areas during the past two days. Additional rises of 1.2 to 1.5 m (four to five ft.) are expected with crests occurring later this week. The river will remain within its banks but pumping stations in valley towns will need to be activated and some other preventive measures may be required. Levels of the Assiniboine River are high but the river will remain within its banks. Levels from Portage la Prairie to Winnipeg will decline during the next few days due to operation of the Portage Diversion.
City of Winnipeg
The Red River level in downtown Winnipeg has risen 1.7 m. (5.5 ft.) during the past two days and stood at five metres (16.5 ft.) this morning. The crest in the Winnipeg area could occur within a few days due to heavy local run-off. A crest of 5.5 m (18 ft.) is expected June 1 to 3. Many basements were flooded late yesterday due to the heavy rain but much of this was due to an overload of weeping tiles rather than sewer backup due to high river levels.
Operation of Flood Control Works
The Red River Floodway will be put into operation this afternoon to help reduce river levels in the city of Winnipeg. Operation of the Portage Diversion commenced at 9 a.m. this morning to reduce high flow on the Assiniboine River coming toward Winnipeg. Dams in the Whiteshell will be operated tomorrow to prevent excessive rises in lake levels.
Weather
Little or nor additional precipitation is expected for the next four days.
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