July 3, 2020
Province Updates High Water Situation in Southwest and Western Manitoba
Manitoba Infrastructure’s Hydrologic Forecast Centre is issuing an update on the flood warning and high water advisory situation in southwest and western Manitoba.
Over the past week, a weather system brought significant precipitation to southwest and western Manitoba. Some areas have received record-high precipitation of more than 200 millimetres during this period. The precipitation has caused water levels to rise in rivers and creeks in these areas.
Widespread precipitation is forecast for most southern, southwest and southeast Manitoba watersheds for the next five to seven days. Occasional heavy thunderstorms could develop at these locations during this time and could bring up to 100 mm of heavy localized rain, which could lead to localized overland flooding.
Property owners are advised to take precautions as water levels could rise significantly in a short time in these areas. Unless travel is necessary, the province requests that individuals stay away from affected areas.
Manitoba Infrastructure crews are working in the flood-affected areas. Staff are monitoring water level conditions and inspecting infrastructure on an ongoing basis, and 11 standard emergency response trailers have been deployed to the Westman area. These trailers contain pumps, water tubes and other essential flood equipment.
On July 1, based on engineering assessments and out of an abundance of caution, the province of Manitoba announced it had lost confidence in the integrity of the dam near Rivers. It recommended the evacuation of people and livestock from approximately 30 to 40 properties along the Little Saskatchewan River downstream of the dam in the rural municipalities of Riverdale and Whitehead. At present, 80 individuals have been evacuated from the RM of Riverdale, four from the RM of Cornwallis, 17 from the RM of Whitehead and three from the town of Neepawa. In addition, livestock has also been evacuated from the RM of Riverdale and the RM of Whitehead.
Manitoba Infrastructure also recommended the immediate suspension of all use of Lake Wahtopanah.
The dam at Rivers is facing a one-in-1,000-year flood event and unprecedented flows on the Little Saskatchewan River following heavy rains and Manitoba Infrastructure indicated there is potential for a structural failure. The dam at Rivers remains intact, but flows are at record levels. Flows at the dam are currently 8,500 cubic feet per second (cfs), a decrease from 12,000 cfs earlier this week.
Manitoba Infrastructure will be monitoring the dam 24-7 until water levels subside. Minor repairs are being completed on an ongoing and as needed basis.
The water level on Lake Wahtopanah has declined 1.5 feet over the past 24 hours and continues to decline but is still at historically high levels.
A flood warning remains in place for the Little Saskatchewan River and Whitemud River watersheds. Both rivers are above flood stage and low-lying land near the rivers are affected.
High water levels on the Whitemud River and are affecting areas near Arden and Gladstone. Levels have peaked at most locations and have started declining, except at Westbourne where water is still rising. The Whitemud River at Westbourne is expected to peak in the next 24 to 48 hours and water is expected to stay within the banks.
A flood warning also remains in place for the Assiniboine River from Brandon to Portage la Prairie.
Overland flooding is being reported in areas across the Assiniboine River watershed. Flooding of low-lying areas is expected for most portions of the Assiniboine River between Brandon and Portage la Prairie. However, water is expected to remain below flood protection levels at most locations along the Assiniboine River.
Operation of the Portage Diversion began yesterday to limit flows in the lower Assiniboine River to 10,000 cfs. The level of Lake Manitoba is currently 811.5 ft., which is in the middle of the desired water level range. The operation of the Portage Diversion is not anticipated to have a significant impact on the level of Lake Manitoba. This operation is in accordance with Portage Diversion operating guidelines. The flow on the Portage Diversion is approximately 700 cfs and the flow on the Lower Assiniboine River near Portage la Prairie is approximately 10,000 cfs. The flow on the diversion should increase to 3,000 cfs over the next 24 hours.
Manitoba Emergency Measures Organization (EMO) staff are working with municipalities to support local emergency preparedness efforts. If required, evacuee reception centres will have physical distancing measures in place.
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