April 7, 2017
FLOOD BULLETIN #10
Manitoba Infrastructure’s Hydrologic Forecast Centre reports overland flooding and tributary flows are beginning to subside across parts of southern Manitoba. Flows in the Assiniboine River are continuing to rise.
Ice is still in place on northern rivers and tributaries, while most rivers in southern Manitoba are ice free.
As of this morning, flow on the Portage Diversion channel is 18,670 cubic feet per second (cfs) (529 cubic metres per second [cms]) and flows on the Assiniboine River downstream of the diversion were increased to 9,000 cfs (255 cms).
The Assiniboine River forecast has been revised based on the forecast of the Assiniboine and Souris rivers peaking simultaneously at the Portage Reservoir. There is also greater confidence in upstream gauge flows as they are no longer ice affected. The revised forecast, with a weather forecast indicating no future precipitation, indicates an inflow upstream of the Portage Reservoir of approximately 41,000 to 44,000 cfs (1,161 to 1,246 cms) between the dates of April 12 to 14. It is planned that flow on the Assiniboine River downstream of the diversion will reach 15,000 cfs (425 cms) as early as April 10. Municipal governments are currently working to put temporary flood protection measures in place to meet the expected flows on the lower Assiniboine River.
Water levels at James Avenue were measured at 18.2 feet this morning. With the floodway in operation, water levels at James Avenue are expected to remain around 18 ft. for the next week as flows on the Red River recede and flows on the Assiniboine River increase. Based on natural Red River flow at James Avenue, this corresponds to a one-in-13-year flood event, with the natural James Avenue peak level of 26.6 ft.
A flood watch remains in effect for the area between Portage la Prairie and Headingley as flows will gradually be increased to about 15,000 cfs by Monday.
A flood watch remains in effect for the Red Deer River but has been lifted for Plum Creek.
A flood warning remains in effect for the Birdtail Creek, upper Assiniboine River from the Shellmouth Dam to Holland, Pelican, Rock, Oak and Dauphin lakes, and the Pembina and Souris rivers. A second crest at Windygates is expected in the next couple of days. The Gretna dike is being monitored for potential overflows from the Pembina River. Equipment is on standby in case a partial road closure is required.
Outflows from Pelican Lake are at maximum possible discharge. Inflows to the lake have crested. However, there is still a large volume of water to come and the lake is projected to rise high enough that flood protection will be required for properties around the lake.
A flood warning remains in effect for all points along the Souris River. Flows on the main stem of the Souris River in Manitoba and the U.S. are continuing to react to the run-off from the melt while tributaries of the Souris River are beginning to decrease.
A high water advisory remains issued for the Carrot River. The Carrot River upstream in Saskatchewan has peaked. Flows at Smoky Burn were recorded yesterday 25,400 cfs (719 cms). An estimated crest of 8,000 cfs (227 cms) on the Carrot River at Turnberry, Sask., is expected in four to seven days. Water levels on the Carrot River within Manitoba are influenced by Carrot River flows and water levels on the Saskatchewan River where the two rivers meet. Conditions will be monitored because the ice is still intact in Manitoba, making ice jamming on both rivers a concern. The backwater effect of ice jamming will influence water levels on the Carrot River. It is difficult to estimate the timing and effects of the upcoming ice jam on the two rivers. More detailed information will be provided to the local municipality by the end of today.
Homeowners affected by this spring’s flooding are reminded to review their home insurance. Overland flood insurance was introduced by some insurers in Manitoba in 2016.
High water levels have led to a number of road closures across the province. People are reminded to be watchful of local waterways, as flood conditions can develop quickly. Ditches and culverts contain fast-moving water which could be hazardous and should be avoided.
Avoid driving through moving water as the water depth can be unpredictable and the current can push vehicles off the road. It is strongly advised that people be careful if venturing out onto what may appear to be frozen rivers and lakes, due to potential weak ice conditions.
For current highway conditions, call 511, visit www.manitoba511.ca or follow the Twitter account at www.twitter.com/MBGovRoads for closures. A Manitoba 511 app is now available for download at http://residents.gov.mb.ca/apps/511.html.
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