Forecasters are estimating that inflows into the Portage Reservoir will reach 53,000 to 56,000 cfs on or around May 14 depending on the impact of rain. To manage these flows, Manitoba Water Stewardship will direct as much as possible towards the Portage Diversion, estimated 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; however, if required, 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.
The controlled release site was selected as it provides for the least risk and best management for the controlled 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 controlled release is being conducted to try and minimize the potential for an uncontrolled breach that would affect 850 homes and the communities of St. Eustache, Elie, St. François Xavier, Poplar Point, High Bluff, Bernard, Fortier, Starbuck, Sanford and LaSalle. An uncontrolled breach of the dike would flood potentially 500 square kilometres of land and would produce a flow of 15,000 cfs, while a controlled release would result in 2,000 to 6,000 cfs and flood approximately 225 sq. km of land.
The release will potentially affect approximately 150 homes and flood land in 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. Approximately 225 sq. km of land will be flooded. Overtopping of the Portage Diversion may affect approximately 40 homes. A special program will be developed to provide comprehensive compensation for these homeowners.
The residences, farms and communities that will be affected by the controlled release are in a risk area for an uncontrolled breach. In that situation, the area could see up to five times the amount of water.
Flood protection including flood-barrier tubes and sandbags are being provided to the RMs of Portage la Prairie and MacDonald. In addition, 100 military personnel will assist today and another 100 tomorrow to help these affected by the controlled release of water through the Assiniboine River dike.
Canadian Forces personnel continue to work along the Assiniboine River dikes to raise and reinforce low-lying areas of the dikes with sandbags. There are currently 604 soldiers and reservists assisting in the flood-fighting effort in Manitoba.
The province has requested the assistance of 300 additional Canadian Forces personnel to assist.
Sandbagging is completed and an additional two feet has been added to the private dikes from Baie St. Paul to Headingley with the assistance of military personnel.
Two provincial sandbag machines have been delivered to the RM of Portage la Prairie. At the request of the Manitoba government, the City of Winnipeg is planning to run their two sandbagging machines 24-7 using city resources to support flood-fighting efforts.
There are several hundred people, including military personnel, working in the area. The Office of the Fire Commissioner has stationed ground and water-rescue boats and crews in the areas.
Evacuations
Residents in the at-risk areas in the RMs of Portage la Prairie, Cartier, St. François Xavier and Headingley, and the homes around the Portage Diversion remain on an evacuation notice and should prepare their evacuation plans. The city of Portage la Prairie is not included in this evacuation notice.
A reception centre is being set up in Portage la Prairie at the Provincial Building on Tupper Street where people who evacuate can register and find additional information and assistance.
Brandon
Work to put up the large flood-tube barriers along PTH 110 is progressing and it may open to truck traffic only later today.
Dike maintenance, reinforcement and pumping are continuing along First Street and 18th Street.
This is a one-in-three hundred year flood in Brandon, surpassing the 1882 flood.
Lake Manitoba
Manitoba Water Stewardship has provided flood maps and notices to municipalities around Lake Manitoba that the lake will reach a level up to 815.6 feet on June 6. As a result, there will be several communities affected and some cottages flooded. Municipalities are examining plans for the best options to manage the high lake level.
Producers who need to move cattle out of the Lake Manitoba area can apply for disaster financial assistance to cover eligible costs such as the costs of transporting cattle, replacing lost feed or inaccessible feed due to flooding and setting up temporary fencing.
General Info
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.
Heavy equipment and trucks loaded with materials to support dike work from Brandon to Headingley are moving throughout southern Manitoba. Caution is advised on all Manitoba highways. Areas where work is underway to raise and reinforce dikes are extremely busy and members of the public are asked to stay away from work areas to ensure the safety of the public and those working on the dikes.
Flood Forecast
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.
High water advisories are in place for all major lakes in Manitoba and the community of Red Deer Lake.
Water levels on the Assiniboine River at the First Street Bridge in Brandon are 1,182.95 ft., increasing 0.21 ft. since yesterday. Flows at the First Street Bridge in Brandon were 37,000 cfs, measured this morning. Peak water levels and dates have been reassessed for the Brandon area to account for forecasted rains. Water level rises are now minor and forecasters are estimating that flows are near crest. Forecasters are anticipating a further 20 millimetres of rain between Thursday and Saturday. Preliminary results of modeling indicate the additional rain will not significantly affect the peak in Brandon.
Flows in the Portage Diversion channel this morning were at 27,200 cfs. Inflow upstream of Portage la Prairie is 45,200 cfs. Flows on the Assiniboine River at the bascule gates were
18,000 cfs this morning. Flows on the river will be gradually increased to 19,000 cfs throughout the day today to manage increasing inflows.
Forecasters are estimating that inflows into the Portage Diversion will reach 53,000 to 56,000 cfs on or around May 14 depending on the effect of rain.
Flows entering the La Salle River watershed from the controlled release may increase current 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 in Winnipeg due to these additional flows expected to reach Winnipeg by May 15 to 20.
The current unstable weather system has brought rain to much of southern Manitoba. Additional unstable weather is forecast to bring a further 20 mm of rain to the Brandon area between now and Saturday. The Dauphin Lake basin is forecast to receive over 50 mm of precipitation between today and Saturday. The forecast rain event will significantly increase tributary flows into Dauphin Lake, further increasing water levels.
Water levels in tributaries into the Dauphin, Winnipegosis and Swan Lake basins have declined recently. However, with the forecast rain event it is anticipated that water levels will increase but stay below previous peaks.
Assiniboine River
Water levels on the Shellmouth Reservoir decreased 0.03 ft. to 1,414.39 ft. Inflow into the Shellmouth Reservoir is approximately 11,660 cfs. The Shellmouth Dam will be operated to maintain outflows around 12,000 cfs today.
St-Lazare’s water levels have decreased 0.16 ft. since yesterday to 1,291.82 ft. St-Lazare’s community flood protection level is 1,294.4 ft.
Water levels at Sioux Valley are 1,203.98 ft. and near crest. Dikes at the Sioux Valley First Nation will provide flood protection to 1,207 ft.
Peak water levels and dates have been reassessed for the Brandon area to account for forecast rains. Water level rises are now minor and forecasters are estimating that flows are near crest. Forecasters are anticipating a further 20 mm of rain between Thursday and Saturday.
Flows in the Portage Diversion channel this morning were at 27,200 cfs. Inflow upstream of Portage la Prairie is 45,200 cfs. Flows on the Assiniboine River at the bascule gates were 18,000 cfs this morning. Flows on the river will be gradually increased to 19,000 cfs throughout the day today to manage increasing inflows.
Dikes along the Portage Diversion channel are being reinforced on both sides of the channel. It is anticipated these improvements will increase channel capacity to around 34,000 cfs (bridge restrictions may reduce this to 32,000 cfs), and potentially reduce the area flooded by dike breaches.
Water levels in the Baie St. Paul area increased 0.02 ft. to 799.94 ft. Water levels in the Lido Plage area decreased 0.03 ft. to 780.28 ft.
Red River
Water levels just upstream of the Red River Floodway inlet are 763.55 ft., with flows of 71,200 cfs. Flows in the floodway are approximately 32,400 cfs.
Water levels on the Red River at James Avenue in Winnipeg have decreased 0.13 ft. to 19.38 ft. Flows at James Avenue this morning were approximately 57,900 cfs.
Souris River
Water levels at Melita are 1,410.12 ft. today, decreasing 0.13 ft. since yesterday.
If the forecast rains occur, water levels on the Souris River are expected to rise. Forecasters have determined the new peak will be less than previous peaks.
Water levels in Oak Lake have increased to 1,412.27 ft., increasing 0.16 ft. since yesterday.
The Souris River at Wawanesa reached 14,700 cfs today.
Lakes
Dauphin Lake water levels have reached flood stage. Communities in the vicinity of Ochre Beach and Dauphin Beach are advised to make necessary flood preparations.
The Dauphin Lake Basin is forecast to receive over 50 mm of precipitation between today and Saturday. The forecast rain event will significantly increase tributary flows into Dauphin Lake, increasing lake levels further.
Water levels in tributaries into the Dauphin, Winnipegosis, and Swan Lake Basins have declined recently. However, with the forecast rain event it is anticipated that water levels will increase but stay below previous peaks.
Maps indicating wind-eliminated inundation areas around the south basin of Lake Manitoba are available on the Manitoba Water Stewardship flood response website at www.gov.mb.ca/waterstewardship/floodinfo/flood_2011.html and have been provided to the rural municipalities surrounding the lake to help landowners prepare for high water levels. It is advisable the public make flood preparations that account for these forecast high water levels.
Water levels on Red Deer Lake are forecasted 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.
For more information, see www.manitoba.ca/flooding. The most up-to-date highway information is at www.gov.mb.ca/mit/roadinfo or 1-877-MBRoads (1-877-627-6237) and on Twitter by following @MBGov.
