April 15, 2015
Province Advises Shellmouth Reservoir Outflows Increased by Another 1,000 Cubic Feet per Second
The Hydrologic Forecast Centre of Manitoba Infrastructure and Transportation reports another increase of 1,000 cubic feet per second (cfs) from the Shellmouth Dam for a total of 4,500 cfs to help draw down the Shellmouth Reservoir. This second crest will continue the over-bank flooding of agricultural land through the Assiniboine River Valley flood plain east of Portage la Prairie. The release from the dam is expected to start reducing the first week of May.
A release of 4,500 cfs would bring a level increase of about three to five feet between the dam and St-Lazare. The highest water between the dam and St-Lazare is expected between April 17 and 20. 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 in the reservoir for rainfall events during the growing season. Higher outflows released earlier helps the river return to within its banks sooner and provides better drainage of flooded lands. Flows on the Assiniboine River would be significantly higher without the dam in place, approximately
6,400 cfs. About 30,000 acres of land along the river has been flooded, but no structures are threatened. The current reservoir level is 428.13 m (1,404.63 ft.). Outflow today was 3,500 cfs.
Daily flow rate sheets will be posted on the government website at: www.gov.mb.ca/mit/floodinfo/index.html
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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