Province decreases outflow from Shellmouth Reservoir

Assiniboine River ice could become unstable

As February wanes away and spring approaches the yearly reduction of flow in the lower Assiniboine has begun.

The Hydrologic Forecast Centre of Manitoba Infrastructure has reduced flows out of the Shellmouth Reservoir this week to 90 cubic feet per second (cfs) from 320 cfs. This could make the ice unstable along the Assiniboine River.

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As flow from the reservoir decreases voids will form under the river ice. This process seriously reduces the carrying capacity of the ice, causing hazardous conditions for those using the river for travel or recreation.

Each winter the Shellmouth dam operates to maintain the lake and downstream flow at levels that will balance the need for reservoir capacity, recreational use on the lake and the health of fish and wildlife in the system.

Before spring melt, a low flow on the Assiniboine makes room for run-off and spring rains. 

The level of the lake has been steadily dropping over the winter, as planned. Current lake levels are at 1397 ft. The target level after spring run-off is 1402 – 1404 ft. above sea level. 


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