Media Bulletin - Manitoba

FLOOD WATCH ISSUED FOR ASSINIBOINE RIVER FROM ST-LAZARE TO BRANDON; HIGH WATER ADVISORY ISSUED FOR SWAN RIVER, DUCK MOUNTAIN AREAS

ASSINIBOINE RIVER WATERSHED

Manitoba Infrastructure and Transportation has issued a flood watch for the Assiniboine River from St-Lazare to Brandon, where the flow is expected to approach the top of the riverbanks, due to heavy rains across Saskatchewan and Manitoba.

A flood warning remains in effect for the Assiniboine River Valley immediately downstream of the Shellmouth Reservoir including the Shellmouth Bridge.

River levels immediately downstream of the dam continue to exceed flood stage.  Further downstream, the river is expected to start rising and approach flood stage as spillway outflow from the Shellmouth Reservoir continues to increase.

• Portions of the upper Assiniboine River are experiencing wet soil conditions as a result of significant storms in the months of April, May and June.  The area has received well above the normal rainfall in April to June.  Due to the wet soil conditions, additional rainfall will result in increased reservoir inflows and levels.
• Significant rain of up to 45 millimetres (mm) has been reported in the last 24 hours in portions of the upper Assiniboine River Basin.  Precipitation amounts of up to 10 mm are forecast over the upper Assiniboine River Basin and southern Manitoba in the next three days.  However, these forecast amounts are uncertain at this point.

River Flow Conditions and Shellmouth Reservoir Operations

• The Shellmouth Reservoir level stood at 1,411.55 feet (ft.) this morning, a rise of 0.35 ft. in the last 24 hours.  The current reservoir level is three ft. above the spillway elevation.  The inflow is 5,900 cubic feet per second (cfs).  The conduit outflow is zero.  The spillway outflow is 3,690 cfs.  This sharp rise is due to significant rain over the reservoir and portions of the upper Assiniboine River Basin.
• Flows over the tops of the riverbanks will continue to affect areas immediately downstream of the dam including the Shellmouth Bridge and Millwood area.  The flows of the Assiniboine River at Kamsack, Sask., and the Shell River at Inglis are 2,940 cfs and 780 cfs respectively.  Since yesterday, the river level near Miniota has risen by 0.75 ft. to a flow of 4,400 cfs.  The flow at the top of the riverbanks at Miniota is close to 5,300 cfs. 
• The Assiniboine River near Brandon has risen by 2.4 inches (in.).  The current flow near Brandon is at 4,300 cfs and flow at the top of the riverbanks at First Street is 8,200cfs.  The river is not expected to overtop banks.
• The Qu’Appelle River flow at Welby, Sask., has remained steady at 1,700 cfs for the last three days.  Some of the Assiniboine River tributaries are experiencing minor rises due to weekend rainfall.  Birdtail Creek and the Little Saskatchewan River have seen minor rises of 2.4 and 1.2 in. respectively since yesterday.  Gopher and Sturgeon creeks are on the decline.  Further tributary rises may occur if significant rains fall in the next few days.
• The operation strategy for the reservoir is continually reviewed with the Shellmouth Reservoir Regulation Liaison Committee, which has representation from municipalities and conservation districts on the reservoir and the river downstream of the reservoir.  Water level conditions of the dam are provided daily to the committee members.