The Hydrologic Forecast Centre of Manitoba Infrastructure reports the risk of widespread major flooding remains low across most of the province, with a continued moderate risk of some overland flooding of low-lying areas along the Red and Assiniboine Rivers.
Ice is expected to start breaking up and moving this week. The Red River Floodway gates will likely be in operation by early next week, based on current weather forecasts. PTH 75 is expected to remain open throughout the run-off period.
The Red River is expected to peak between approximately 50,000 and 60,000 cubic feet per second (cfs) between April 27 and May 2 at Ste. Agathe. The peak will reach Winnipeg within 48 hours after the peak at Ste. Agathe. This flow is similar to the one observed in 2017, which was 54,000 cfs at Ste. Agathe. The peak water level at James Avenue in Winnipeg is expected to be approximately 19.0 ft. Last year, for similar flows, the peak level at James Avenue was 19.1 ft.
The Portage Diversion could start operation in the week of April 23 for ice control along the lower Assiniboine River. Flows along the Assiniboine River at Portage la Prairie could reach just over 20,000 cfs, which would require the use of the Portage Diversion to limit the downstream flow to 12,000 cfs. The Shellmouth Dam will continue operations to reach summer levels after the spring run-off.
The risk of major flooding continues to be low for the Souris, Qu’Appelle and Pembina rivers and their tributaries. Levels will be within flood protection levels even with unfavourable weather conditions. The risk of major flooding in the Interlake region and for most major lakes, including Lakes Winnipeg, Manitoba and Dauphin and the Whiteshell lakes is low. The risk of major flooding is moderate on northern basins including the Churchill and Carrot rivers in The Pas region.
Ice-jam related flooding continues to be a possibility due to the thickness of the ice on some of Manitoba’s rivers and streams. Icebreaking activities have been completed at all locations that have been at high risk of ice jamming in past years.
