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Media Bulletin - Manitoba

April 14, 2015

Province Advises Outflows Increased From Shellmouth Reservoir to Make Room for Future Storage



The Hydrologic Forecast Centre of Manitoba Infrastructure and Transportation reports that prolonged high inflows to the Shellmouth Reservoir will require higher outflows from the Shellmouth Dam resulting in overbank flooding on the upper Assiniboine River.

Flows up to 3,500 cubic feet per second (cfs) are expected to be released by 9 a.m. tomorrow.  The river is expected to rise and continue flooding some low-lying land.  A release of 3,500 cfs would bring a level increase of about two to four feet between the dam and St. Lazare.  The highest water between the dam and St. Lazare is expected between April 15 and 17.  Downstream of St. Lazare the peak will be lower than that observed in early April.  Water levels are expected to drop below the bank by the end of this month.

The outflows are being increased to slow the rate the reservoir is rising and to preserve some storage space on the reservoir for the growing season.  Higher outflows now may allow the dam and reservoir to be used to prevent potential flooding later in the year, during the growing season.  The current inflow into the reservoir is 6,800 cfs, and without the dam, flows on the Assiniboine River would be significantly higher, also at approximately 6,800 cfs.  Inflow is expected to decline gradually.  The current reservoir level is 427.97 m (1,404.10 ft).  Outflow today was 2,500 cfs. 

The Shellmouth Dam and Reservoir are operated in consultation with the Shellmouth Reservoir Regulation Liaison Committee.  The committee has been meeting on a daily basis to discuss and advise on operation.

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