Severe flooding across Manitoba this spring.
Flows on the Assiniboine River into the Portage Reservoir have increased to 50,700 cfs from 48,550 cfs since yesterday. The Portage Diversion flow is 32,000 cfs at this time. The technical assessment is the Portage Diversion will be able to convey 34,000 cfs safely but with possible overflow at the north end.
Flows on the Assiniboine River downstream of Portage La Prairie were decreased to 18,000 cfs due to concerns regarding the Assiniboine River dikes.
Forecasters are estimating that inflows into the Portage Reservoir will reach 54,000 to 56,000 cfs, with the higher range of flows anticipated to reach the reservoir on or around May 19 to 21. To manage these flows, Manitoba Water Stewardship will direct as much as possible through the Portage Diversion, estimated to divert as much as 32,000 to 34,000 cfs. All efforts will be made to keep flows in both the diversion and the river.
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
No controlled release is planned today. The current plan is for the initial release of water to commence early on Saturday, May 14. After a few hours, the flow would be approximately 500 cfs. This amount would be continually reassessed and modified as necessary. Based on the current forecast, the controlled release flows could gradually increase to between 2,500 and 3,000 cfs over the following days.
This could change if an uncontrolled breach occurs on the Assiniboine River dikes and the release is required on an emergency basis.
The additional capacity at the Portage Diversion is allowing residents more time to prepare and additional time to reinforce and strengthen the Assiniboine River dikes. The site of the controlled release is part of a much larger area that would be flooded in an uncontrolled breach. A planned and controlled release would allow the water flow to be managed and spilled slowly, which would not be possible with an uncontrolled breach.
The additional time also allows for flood-fighting efforts including giving provincial crews time to survey properties in the area affected by the controlled release, providing residents information about potential water levels and the steps needed to protect their homes and property.
The controlled release would help relieve pressure on the Assiniboine River dikes that are protecting communities and homes from Portage la Prairie to Headingley, and help to protect against the risk of an uncontrolled dike break and outbreak of water. It would also help address flows going into the Portage Diversion channel, and if an uncontrolled occurs, then the controlled release will help reduce the potential harm and provide time for repairs.
The controlled release is not expected to adversely affect the communities of Starbuck, Sanford and La Salle. However, as a precautionary measure, residents along the river are putting flood- proofing measures in place. Manitoba Water Stewardship will provide the municipalities with information about flood-protection levels.
Evacuations
So far, 14 homes in the immediate area of the planned, controlled release through the Assiniboine River dikes have been evacuated and flood-protection systems have been put in place.
In addition, 39 notices have been given to homes that may be affected by spillover from the Portage Diversion and flood protection systems have been put in place at these homes.
Extensive resources are being provided to protect against flooding in the area that will be affected by the controlled release.
Several thousand households in areas that would be at risk of flooding under an uncontrolled breach scenario have been placed on precautionary evacuation notices by the RMs of Portage la Prairie, Cartier, St. François Xavier and Headingley. Residents should maintain a high level of readiness to evacuate should the dikes breach in an uncontrolled manner.
Portage Diversion Upgrades
Increasing the capacity of the Portage Diversion to handle additional flows has allowed more time for residents potentially affected by the controlled spill to prepare and additional time to strengthen and reinforce the Assiniboine River dikes.
Work on the diversion includes:
• raising the south dike of the Portage reservoir
• raising the diversion channel dikes on both sides by approximately three feet
• providing erosion protection work around the structures in the channel
• installing a gas generator to ensure the gates can be managed if electrical power is affected by rising waters
• installed back-up hydraulic pumps to lift the gates, and
• adding rock on the diversion structures and around the bridges crossing the diversion channel including rail bridges to add stability.
In the last two summers, the diversion reservoir was dredged and vegetation was removed from the channel, removing obstacles and allowing for more efficient water flow.
Putting these additional measures in place could allow the Portage Diversion to handle up to 34,000 cfs, which is above its design capacity of 25,000 cfs.
Assiniboine River Dikes
Provincial staff and 300 Canadian Forces soldiers are sandbagging along the provincial dikes from Portage la Prairie to Baie St. Paul. Nine helicopters are ferrying sandbags into areas that are hard to access. These dikes are being monitored on a 24-7 basis against a potential uncontrolled breach.
Provincial staff, with the assistance of 200 Canadian Forces soldiers, are working to protect properties that will be affected by the Portage Diversion spillover and will be moving to protect properties in the Elm River Channel that would be affected by a controlled release and spill through the Assiniboine River. Volunteers and municipalities are sandbagging and putting up other flood-protection measures around properties that may be affected by the furthest reaches of a controlled spill.
Today more than 450,000 sandbags are being distributed to the RMs of Alonsa, Portage la Prairie, St. François Xavier, Elie and Brandon.
Brandon
The City of Brandon has extended evacuations to include the Corral Center and The Paddock along 18th Street. There are 1,326 people evacuated in Brandon.
The province has provided 50,000 sandbags to the City of Brandon today.
Assiniboine Community College and the residences at Brandon University will be used by the City of Brandon to house evacuees in need of a place to stay over the weekend.
Other Areas
Heavy rains, as much as 100 millimetres in Saskatchewan, are causing increased flows on the Qu’Appelle River at the community of St-Lazare. Sections of the community ring dike, and municipal and private dikes are being raised another foot. Provincial crews and Aquadams, (large flood-tube barriers) are heading into the area to assist with the work.
In Dauphin Lake, approximately 45 homes/cottages are currently affected along Lake Dauphin in the RM of Ochre River. Another 150 spots could be affected if the levels continue to rise. The RM of Ochre River is monitoring the levels on one municipal road and may need to evacuate some homes.
The Manitoba Association of Native Firefighters (MANFF) has co-ordinated the evacuation of
15 people from the Skownan First Nation near Waterhen .
MANFF has also co-ordinated the evacuation of 11 people from the Pinaymootang First Nation because of a loss of safe road access.
There are currently 1,341 Canadian Forces soldiers and reservists assisting with flood-fighting efforts in Manitoba.
Two provincial sandbag machines are working in Winnipeg, two have been located to Portage la Prairie and one is the RM of St. Laurent and one is in the Crane River area. The City of Winnipeg is also operating two sandbag machines to support flood-fighting efforts.
There currently 3,169 Manitobans evacuated from their homes.
As a precautionary measure, the Office of the Chief Provincial Public Health Officer has issued a boil-water advisory for those using private, untreated water sources such as well water or surface water for drinking water in flooded areas. The Manitoba government will once again cover the costs of testing drinking water supplies once flooding has ended.
The south closure of the St. Adolphe ring dike is being opened today. The north closure at St. Adolphe remains closed. PR 210 south of St. Adolphe has been opened.
There are 122 provincial roads affected by flooding, 73 closed. There are approximately 750 municipal roads closed.
Assiniboine River
Water levels on the Shellmouth Reservoir are 1,414.47 ft., unchanged from yesterday. Inflow into the Shellmouth Reservoir is approximately 12,120 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 one to two days. This operational plan will prevent Shellmouth outflows from further increasing crests downstream to Portage la Prairie.
This recent 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, which is a new, higher peak. Water levels in Brandon are forecast to reach between 1,183.4 ft. and 1,183.8 ft. between May 18 and 20.
Water levels on the Qu’Appelle River, a major tributary of the Assiniboine River, increased significantly yesterday as a result of recent rains. The Qu’Appelle River peaked at 13,300 cfs around midnight last night and receded to 12,500 cfs this morning. Impacts of these high flows have been included in the Assiniboine River forecast for today. St-Lazare’s water levels have increased 0.23 ft. since yesterday to 1,292.21 ft. St-Lazare’s community flood-protection level is 1,294.4 ft.
Miniota’s water levels have increased 0.09 ft. since yesterday to 1,247.21 ft.
Water levels at Sioux Valley are 1,203.88 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 1,182.55 ft., decreasing 0.16 ft since yesterday. Flows at the First Street Bridge in Brandon were 37,500 cfs, measured this morning. This is a one-in-300-year flood event in Brandon, surpassing the 1882 flood.
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 1,183.4 to 1,183.8 ft. at First Street Bridge in Brandon between May 18 and 20. It is estimated that flows on the Assiniboine River at Brandon will be sustained for the next few days.
Flows in the Portage Diversion channel this morning are at 32,000 cfs. Inflow upstream of Portage la Prairie is 50,000 cfs. Flows on the Assiniboine River at the bascule gates were 18,000 cfs this morning.
The feasibility of increasing flows on the Portage Diversion to 34,000 cfs is being assessed. It is unlikely the Assiniboine River dikes can hold more than 19,000 cfs today. Assiniboine River dikes are seeping in different locations. Efforts to increase Assiniboine River capacity are ongoing.
Flows on the Assiniboine River at Holland are 51,200 cfs.
Dikes along both sides of the Portage Diversion channel are being reinforced. It is anticipated that these improvements will increase channel capacity to around 34,000 cfs (bridge restrictions may reduce this to 32,000 cfs), and reduce the need to add to flows to the controlled release.
There is more water running in the Portage Diversion than the Red River Floodway.
Water levels in the Baie St. Paul area have increased to 800.2 ft. Water levels in the Lido Plage area increased 0.1 ft to 780.41 ft.
Red River
Water levels just upstream of the Red River floodway inlet are 763.26 ft., with flows of 69,100 cfs. Flows in the floodway are approximately 31,800 cfs.
Water levels on the Red River at James Avenue in Winnipeg have decreased 0.25 ft. to 19.08 ft. Flows at James Avenue this morning were approximately 56,600 cfs.
Flows entering the La Salle River watershed from the controlled release will increase flows on the La Salle River by between 2,500 to 3,000 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 would be as much as 1.5 ft. at James Avenue at the highest projected La Salle River inflow.
Souris River
Water levels at Melita are 1,410.07 ft. today, decreasing 0.12 ft. since yesterday.
Water levels on the Souris River are expected to rise as a result of the recent rain event. Forecasters have estimated the new peak will be slightly less than previous peaks.
Water levels in Oak Lake are 1,412.17 ft. Water levels on Plum Creek have increased 1.31 ft. since yesterday to 1,376.68 ft.
The Souris River at Wawanesa reached 15,800 cfs today with a water level of 1,156.43 ft. Forecasters have assessed the impacts of recent rains on the Souris River. The Souris River at Wawanesa may reach 16,000 to 17,000 cfs between May 13 to 15.
Dauphin Lake, Swan Lake and Lake Winnipegosis Basins
Streams and rivers responding to the recent rain event were highest in the Dauphin Lake, Lake Winnipegosis and Swan Lake Basin. Water level changes since yesterday include:
• the Roaring River increased 3.03 ft.;
• the Swan River increased 2.38 ft.;
• Wilson Creek increased 2.28 ft.;
• the Turtle River increased 0.24 ft.;
• the Ochre River decreased 0.49 ft.; and the Valley River increased 0.43 ft.
Lakes
Dauphin Lake water levels have reached flood stage. Residents and cottages in the vicinity of Ochre Beach and Dauphin Beach are advised to make necessary flood preparations. Forecasters have increased the Dauphin Lake crest to 860.5 ft., higher than previous forecasts.
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 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 are estimated at 14,200 cfs as of late yesterday.
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.
