A forecast fifth major rain storm is raising serious flood concerns and will be closely monitored over the next four days. Four major storms have already fallen on saturated soils affected by heavy flooding in the Assiniboine and Souris river watersheds. The cumulative effects of the flood and sustained storms are pushing the capacity of Manitoba’s flood-protection systems to or beyond their design capacity. As a result, the Manitoba government is reassessing all flood-protection measures at its disposal.
Work to reinforce the Assiniboine River dikes and the Portage Diversion channel is underway once again. Preliminary estimates show projected flows into the Portage Reservoir could reach 53,000 cubic feet per second (cfs) in the next seven to 10 days, with up to 34,000 cfs being directed down on the Portage Diversion channel and up to 19,000 cfs along the Assiniboine River dikes, depending on how much rain actually falls. Due to the repeated storms, the diversion is expected to run over its design capacity by up to 9,000 cfs once again. The effect of the high flows on the Assiniboine dikes will also need to be continuously monitored.
As a result of the high flows on the Portage Diversion channel, evacuation alerts will be reissued by the RM of Portage la Prairie to 45 homes near the channel.
Flood forecasters will be watching the forecast storm very carefully and will operate all flood-protection measures to their utmost capacity to deal with the expected rainfall.
Residents with flood-protection systems in place along the Assiniboine and Souris river basins are advised to maintain and monitor sandbag and other diking systems in the next few days.
The high flows on the Portage Diversion channel into Lake Manitoba protect homes and communities between Portage la Prairie and Headingley, and communities in the La Salle River watershed.
The Souris River basin has received almost 300 per cent of normal precipitation and areas of the Assiniboine River basin have received between 150 and 250 per cent of normal. The maps at www.manitoba.ca/flood show precipitation levels experienced this spring.
The repeated storms, which have produced record rains in some instances, have had a significant and quick effect on already high water levels. Flood forecasts will continue to change and be updated based on the effects of rainfall.
The 2011 flood is a flood of record and high water levels are expected to continue through the summer and into the fall. The flood on the Assiniboine River at Portage la Prairie is a one-in-350-year event.
Record flooding is occurring in Manitoba, Saskatchewan and North Dakota.
Unusually high flows into Lake Manitoba from the Portage Diversion and the Waterhen and Whitemud rivers have resulted in a special Lake Manitoba compensation program under the $175-million Building and Recovery Action Plan announced in late May.
Other Areas
Evacuations of approximately 14 people occurred in the Westbourne area due to a loss of safe road access and high water from the storm.
The town of Oak Lake has experienced significant overland flooding and is pumping and monitoring homes at risk of basement flooding.
Construction and reinforcement of the dikes in The Pas is also continuing to prepare for high flows coming from Saskatchewan along the Saskatchewan River.
Approximately 33 provincial and federal government employees will be working in the Lundar area today to assist with sandbagging.
Sandbag machines are working in Crane River, Ste. Rose du Lac, Winnipeg and at the Brandon Correctional Centre producing sandbags for Lake Manitoba communities including Dauphin Lake, Ochre Beach and Meadow Portage. Sandbags are being made and delivered to communities to raise dikes due to rising Lake Manitoba levels.
A one-stop office for St. Laurent and Woodland residents opened today and will provide flood recovery services at the RM of St. Laurent Municipal Office, until June 11 between 10 a.m. to 5 p.m. The office will help residents apply for the Lake Manitoba Financial Assistance program and provide information about other available services.
At Oak Lake, construction work is being done on the dikes to maintain road access and protect cottages.
Work is continuing in The Pas to reinforce and construct permanent dikes in preparation for high flows from Saskatchewan on the Saskatchewan River.
Flood Forecast
All wind warnings issued by Environment Canada in Manitoba have ended. Winds are forecast to be generally light for the next few days. There are no wind set-up alerts for today.
Water levels on the Whitemud River are expected to rise as a result of recent rains. Water levels near Keyes increased 2.8 feet yesterday to 952.59 ft.
Based on the recent and forecasted storms, a revised forecast for the Souris River at Wawanesa shows peak flows are estimated to reach between 1,158 and 1,159.3 ft. around June 10 to 12.
Water levels on Oak Lake remain very high.
Water levels on the Little Saskatchewan River and Oak River experienced a significant increase over the last two days as the result of recent rain events; however, the rivers are now declining at all points, including Rivers Reservoir and Minnedosa Reservoir.
Water levels on the Saskatchewan River near The Pas are expected to reach 855.5 to 857 ft., depending on the weather.
On Rock Lake, water levels began increasing around May 31 and reached a minor crest of 1,337.48 ft. on June 5. Since June 5, water levels have begun declining to their current levels of 1,336.67 ft. The outlet at Pelican Lake has been operating at full capacity since June 5 and remains open at a flow of 424 cfs.
Water levels on the Saskatchewan River at The Pas increased 0.09 ft. since yesterday to 853.55 ft, with a flow of 63,500 cfs. Water levels are expected to reach 855.5 and 857 ft., by late June, depending on the weather.
Lakes
Based on recent storms, the new forecast for Lake Manitoba ranges between 816.8 and 817 ft. around mid-July. Lake St. Martin water levels are forecast to reach between 806 and 806.2 ft. around early August, depending on weather.
The estimated outflow from the Fairford River water control structure is 18,600 cfs today. The structure continues to operate at full capacity due to the high level of Lake Manitoba.
Assiniboine River
The Assiniboine River watershed is forecast to receive rain early next week. Flood forecasts are being updated do to reflect these weather conditions.
Water levels on the Qu’Appelle River at Welby are 16.5 ft. today, increasing 0.03 ft. since yesterday.
Water levels on the Shellmouth Reservoir are 1,408.03 ft. decreasing 0.29 ft. since yesterday. Inflow into the Shellmouth Reservoir is 3,130 cfs and outflow is 4,500 cfs today.
Operations at the Shellmouth Reservoir will be adjusted so that conduit flows equal reservoir inflows. As a result, the reservoir elevation will be static. This operation is to provide relief for the Portage Diversion inflow and help deal with future weather conditions.
Water levels on the Assiniboine River at the First Street Bridge in Brandon are at 1,179.98 ft., increasing 0.2 ft. since yesterday. Flows at the First Street Bridge are estimated to be 26,300 cfs.
Inflow upstream of Portage la Prairie is 48,490 cfs. Flows in the Portage Diversion channel are 30,460 cfs. Flows on the Assiniboine River at the Portage Reservoir control gates are 18,080 cfs. The recent storm and the forecasted rain will increase flows.
Water levels in the Baie St. Paul area are 799.99 ft., decreasing 0.03 ft. since yesterday.
Souris River
The Souris River basin received significant rainfall in the past few days. Forecasts are being updated to reflect this recent rain event.
Plum Creek decreased 0.33 ft. since yesterday to 1,376.72 ft.
Water levels on the Souris River are 1,411.29 ft. at Melita, 1,360.79 ft. at Souris and 1,158.76 ft. at Wawanesa.
