The recent storm brought significant rain to the eastern Saskatchewan and the western Manitoba region and will affect the flood forecast. Areas receiving the most rain include the Shellmouth Reservoir area with between 25 and 40 millimetres, the Swan River Basin with 25 to 35 mm, and the Lake Winnipegosis Basin with between 20 and more than 35 mm. Flows are increasing quickly on streams and rivers, with rises in the North Duck River of 3.19 feet, and one ft. on the Swan and Pine rivers. It is anticipated the new crest on the Pine River will be higher than previous peaks.
Peak water levels and dates have been reassessed for the Brandon area to account for the recent storm event. Forecasters are estimating that flows may increase to 39,000 to 41,000 cfs and 1,183.15 to 1,183.45 ft. at the First Street Bridge in Brandon on May 18. The Brandon dikes are high enough to deal with this level of water.
Flood warnings have been issued for the Assiniboine River at all points downstream of the Shellmouth Dam; streams and rivers in the Dauphin Lake Basin; streams and rivers east of the Duck Mountains; the Souris River from Melita and all downstream reaches; Pipestone Creek, all reaches; Oak Lake and Plum Lakes; Plum Creek to the Souris River (including the town of Souris); and the Qu’Appelle River in the St-Lazare area.
A high water advisory is in place for all major lakes in Manitoba and the community of Red Deer Lake.
Flood Response
Three key activities are underway to handle high Assiniboine River flows between Portage la Prairie and Headingley. the activities include increasing the capacity of the Portage Diversion to handle more water from the river, strengthening dikes to help manage high flows for a sustained period of time, and planning and preparing a controlled release and spill of the river in a contained and limited area. The recent rain has added to the flows in the Assiniboine River watershed and will result a change to the flood forecast.
The controlled release being planned through the Assiniboine River dikes tomorrow morning at approximately 8 a.m. The release will be delayed as long as possible to give residents in the area time to prepare.
The initial release of water would be approximately 2,000 cubic feet per second (cfs) and may gradually increase to 3,000 cfs within 24 hours. This will be continually reassessed and modified as necessary. This planned release would cause overland flooding in the area, but it will be a slow and controlled release of water that would slowly move through the area. Homes that would be the first to be impacted by the release have already been evacuated and are being protected with flood tubes that are being placed by 100 Canadian Forces soldiers. A special program is being developed to provide comprehensive compensation to affected homeowners and producers.
Heavy equipment will be stationed south and east of the controlled release site to help control the flow of water.
The controlled release site was selected as it provides for the least risk and best management for the release. It is the closest location to the La Salle watershed and provides the most predictable flow of water after the release. It is also the most reliable site for equipment and workers to manage the release. Other areas are not accessible due to current conditions. The site also provides the maximum relief to areas downstream of the Portage Diversion between Portage la Prairie and Headingley.
The area affected is the La Salle watershed near Elm River, the Elm River channel, the Elm River relief channel, the Scott Coulee, the Scott drain and the La Salle River downstream of the Elie dam and reservoir.
Along the Assiniboine River dikes, provincial staff and 300 Canadian Forces soldiers will help fortify the dike. Approximately 200 soldiers are working to protect 39 properties in the path of the spillover from the Portage Diversion.
At the Portage Diversion, extensive work has been underway to strengthen the structure, and raise and reinforce the channel to handle additional flows. Maintenance work undertaken at the diversion in the fall increased the ability of the channel to carry additional flows.
Forecasters are estimating that inflows into the Portage Diversion will reach 54,000 to 56,000 cfs, with the higher range of flows anticipated reach the reservoir on or around May 19. To manage these flows, Manitoba Water Stewardship will direct as much as possible through the Portage Diversion. This could divert as much as 32,000 to 34,000 cfs. A further 19,000 cfs will be directed into the river. All efforts will be made to keep flows in both the diversion and the river. The remainder of flows, between 2,000 and 6,000 cfs, will be released into the La Salle River watershed through a controlled release through the Assiniboine River dikes.
Improvements at the Portage Diversion are anticipated to increase channel capacity to around 34,000 cfs (bridge restrictions may reduce this to 32,000 cfs) and reduce the flow in the river downstream of the diversion.
The Manitoba government has a state of emergency in place to cover the following areas: the city of Portage la Prairie and the RMs of Portage la Prairie, Woodlands, Rosser, St. François Xavier, Headingley, Cartier, Macdonald and Grey.
Evacuations
Residents in the area around the controlled release, the Portage Diversion spillover and along the Assiniboine River dikes should be on a high level of alert for possible evacuation, as conditions are subject to change. Residents are advised to follow instructions from their local rural municipalities and local authorities.
Brandon
PTH 110 is open to truck and emergency traffic with a pilot vehicle escort. There are large flood-tube barriers on either side of the road.
Canadian Forces are continuing to assist with monitoring and reinforcing the dikes along First Street and 18th Street.
Extensive flood-fighting efforts continue in the city by provincial, military and municipal staff to reinforce and monitor dikes as required.
There are currently 1,231 people evacuated, with approximately 600 staying in hotels.
Other Areas
There are approximately 1,000 Canadian Forces soldiers and reservists assisting with flood-fighting efforts across the province.
Flood-fighting equipment, including flood-tube barriers, sandbag machines, sandbags and other material, will be carefully targeted to areas of most need that face the most imminent flood threat. Priorities will be critical infrastructure, communities and homes.
Approximately 424 people have been evacuated from the Lake St. Martin First Nation.
Significant work is underway to construct dikes at the Little Saskatchewan First Nation near Lake Manitoba.
The Manitoba government remains committed to a special program to deal with the impact of flooding in the Lake St. Martin area.
Approximately 53 people from the Long Plain First Nation have been evacuated due to high levels on the Assiniboine River.
Sandbagging of properties in the Dauphin Lake area is underway and the lake has hit flood stage.
The south closure of the St. Adolphe ring dike is being opened today. The north closure at St. Adolphe remains closed.
Across Manitoba there are 2,906 people evacuated from their homes.
There are currently 120 provincial roads affected, with 72 closed. There are 784 municipal roads closed, affecting approximately 2,700 kilometres of roads.
Producers who need to move feed to livestock or move livestock from flooded or potentially flooded areas are doing so with assistance of local municipalities and Manitoba Agriculture, Food and Rural Initiatives (MAFRI). MAFRI and Manitoba Conservation staff are working to identify Crown lands that can house livestock and store machinery. Current information on crops is available on line at www.gov.mb.ca/agriculture/crops/cropreports/pdf/cr.pdf.
Producers with questions or who need assistance should first contact their local RM for direction. Agricultural information is also available from local GO offices. Producers who have facilities or pasture land available for affected livestock are asked to contact the local GO MAFRI office.
Assiniboine River
Water levels on the Shellmouth Reservoir have increased 0.08 ft. to 1,414.47 ft. Inflow into the Shellmouth Reservoir is approximately 12,740 cfs. The Shellmouth Dam will be operated to maintain outflows around 12,000 cfs today and will be maintained at this level for the next two to three days. This plan will prevent Shellmouth outflows from further increasing crests downstream to Portage La Prairie. The inflow forecast will be updated later today to assess the impacts of the recent rainfall and long-term outflows. The recent rain brought between 30 and 40 mm in the Shellmouth Reservoir area, which will result in further water level increases over the next few days.
The rain will likely result in another crest on the Assiniboine River between the Shellmouth Dam and Portage la Prairie. The crest at Russell is forecast to be higher than previous peaks. Forecast crests on the Assiniboine River at St-Lazare and near Miniota will likely be similar to last week’s crest.
Flows on the Assiniboine River at Brandon will likely increase to a forecast 39,000 to 41,000 cfs, with a new, higher peak between 1,183.15 and 1,183.45 ft on May 18. The Brandon dikes are high enough to deal with this level of water.
Water levels on the Qu’Appelle River, a major tributary of the Assiniboine River, are increasing as a result of recent rains. The peak inflow from the Qu’Appelle River will be higher than the May 6 peak.
St-Lazare’s water levels have decreased 0.12 ft. since yesterday to 1,289.33 ft. St-Lazare’s community flood protection level is 1,294.4 ft.
Miniota’s water levels have increased 0.03 ft. since yesterday to 1,247.12 ft.
Water levels at Sioux Valley are 1,203.93 ft., decreasing 0.05 ft. since yesterday. Dikes at the Sioux Valley First Nation will provide flood protection to 1,207 ft.
Water levels on the Assiniboine River at the First Street Bridge in Brandon are 1,182.71 ft., decreasing 0.24 ft. since yesterday. Flows at the First Street Bridge in Brandon were 37,540 cfs, measured this morning. This is a one-in-three-hundred year flood event in Brandon, surpassing the 1882 flood.
Flows in the Portage Diversion channel this morning were at 29,600 cfs. Inflow upstream of Portage la Prairie is 48,550 cfs. Flows on the Assiniboine River at the diversion were 19,000 cfs this morning.
The feasibility of increasing flows on the Portage Diversion to 34,000 cfs and the ability of the Assiniboine dikes to handle 20,000 cfs is being assessed. At this point, the Assiniboine River dikes are unable to sustain flows greater than 19,000 cfs.
Water levels in the Baie St. Paul area are 800 ft. Water levels in the Lido Plage area increased 0.03 ft. to 780.31 ft.
Red River
Water levels just upstream of the Red River floodway inlet are 763.35 ft., with flows of 70,700 cfs. Flows in the floodway are approximately 32,100 cfs.
Water levels on the Red River at James Avenue in Winnipeg have decreased 0.05 ft. to 19.33 ft. Flows at James Avenue this morning were approximately 57,700 cfs.
Flows entering the La Salle River watershed from the controlled release may increase flows on the La Salle River by between 2,000 cfs to 6,000 cfs. The La Salle River is a tributary which flows into the Red River downstream of the floodway inlet. It is anticipated that water level rises on the Red River will be approximately 1.5 ft. higher at James Avenue at the highest projected La Salle River inflow.
Souris River
Water levels at Melita are 1,410.12 ft. today, with no change since yesterday.
Water levels on the Souris River are expected to rise as a result of the recent rain event. Forecasters have determined the new peak will be less than previous peaks.
Water levels in Oak Lake are 1,412.24 ft. Water levels on Plum Creek have increased 0.22 ft since yesterday to 1,375.36 ft.
The Souris River at Wawanesa reached 15,000 cfs today with a water level of 1,156.3 ft. Forecasters have assessed the impacts of recent rains on the Souris River. The Souris River at Wawanesa may reach 16,000 cfs on or around May 14.
Dauphin Lake, Swan Lake and Lake Winnipegosis Basins
The recent rain has significantly increase tributary flows in the Lake Winnipegosis, Swan Lake and Dauphin Lake basins, resulting in increased lake levels.
Streams and rivers with the highest increases from rain are in the Dauphin Lake, Lake Winnipegosis and Swan Lake basins. Water level changes since yesterday include:
– the Vermillion River increased 5.26 ft.; – the North Duck River increased 3.19 ft.; – the Turtle River increased 3.08 ft.; – the Ochre River increased 2.94 ft.; – the Valley River increased 1.53 ft.; – the Wilson Creek increased 1.46 ft.; – the Roaring River increased 0.98 ft.; and – the Swan River increased 0.73 ft.
Lakes
Forecasters have increased the Dauphin Lake crest to 860.5 ft., higher than previous forecasts.
The recent rain has significantly increased tributary flows into the Swan Lake and Lake Winnipegosis basins, resulting in increased lake levels.
Maps indicating wind-eliminated inundation areas around the south basin of Lake Manitoba are available on the Manitoba Water Stewardship flood response website and have been provided to the rural municipalities surrounding the lake to help landowners prepare for high water levels. The public in the affected area are advised to make flood preparations that account for these forecast high water levels.
Water levels on Red Deer Lake are forecast to reach flood stage. A high water advisory has been issued for the community of Red Deer Lake. It is advisable the community make necessary flood preparations.
Outflows from Lake Manitoba were estimated at 14,200 cfs as of late yesterday. This flow value will be assessed later today.
Forecasters have estimated peak wind-eliminated water levels for Lake Manitoba and Lake St. Martin; both are forecast to reach high water levels that are unprecedented since regulation of the lakes began in 1961. These forecast elevations are preliminary at this time and may be revised with major weather changes and as computer models are refined.
The risk of shoreline ice pile up today is low on all assessed lakes.
For more information, please see www.manitoba.ca/flooding and find the most up-to-date highway information at www.gov.mb.ca/mit/roadinfo or 1-877-MBRoads (1-877-627-6237) and on Twitter by following @MBGov.
