June 2, 2010
High River Levels, Forecasted Rain, Wet Conditions Lead to Further Red River Floodway Operations to Reduce Basement Flooding Risk
· Manitoba Water Stewardship advises the Red River Floodway gates will be further raised starting at 6 p.m. today to divert additional flows into the floodway channel.
· An assessment of the conditions has resulted in a decision to raise the floodway gates in accordance with its floodway rules of operation to reduce the risk of widespread basement flooding in Winnipeg from the rainfall expected late tomorrow and on the weekend.
· The assessment showed the level of the Red River at James Avenue was 5.5 metres (17.9 feet) and, without this additional operation, it is expected to decline very slowly. The wet conditions from last weekend’s major storms will increase the amount of run-off into the sewer system from the expected rainfall, which will add to the risk of basement flooding. The combination of the high river levels and wet conditions mean the benefits of this operation could be substantial, depending on the intensity of the rainfall that actually occurs.
· This operation will cause a gradual rise of the river level at the floodway inlet of about 1.5 m
(five ft.) to the prairie level of 231.6 m (760 ft.) above sea level. This level would be maintained until about mid-June based on average precipitation but could extend longer if heavy rains continue.
(five ft.) to the prairie level of 231.6 m (760 ft.) above sea level. This level would be maintained until about mid-June based on average precipitation but could extend longer if heavy rains continue.
· The provincial government will provide compensation to landowners for damages caused by artificial flooding resulting from the operation of the floodway above natural levels.
· Summer river levels this high have only occurred five times since the early 1900s.
· The floodway gates were first raised during this weather event May 30 to begin diverting rising waters as a result of storms of May 28 and 29.
· The flow into the floodway today was 5,580 cubic feet per second (cfs) and the total flow at the floodway inlet was 47,250 cfs.
Weather Forecast
· Rainfall of about 10 to 15 millimetres (0.4 to 0.6 inches) is expected Thursday evening through Friday. There is a possibility of thunderstorms which could bring heavier rainfall. Additional rainfall is predicted for Saturday.
Overland Flooding and Small Streams Update
· Overland flooding continues due to overloaded ditches and drains but conditions are gradually improving. Most smaller streams have crested and will decline slowly for the rest of this week. The additional expected rain may slow down the rate of decline or cause minor rises in some areas. Additional rainfall will lengthen the duration of overland flooding.
Red River
· Rises of the Red River since yesterday have been minimal and a gradual decline will commence tomorrow. The Red River is now at or near its crest from Emerson to Selkirk. It has crested a little earlier than expected due to a significant decline in inflows from Manitoba tributaries. The river is within its banks at all points. The rain expected late tomorrow to Friday will reduce the rate of decline.
· The river level in downtown Winnipeg declined about 7.6 centimetres (three in.) since yesterday and stood at 5.5 m (17.9 ft.) this morning.
Assiniboine River
· The Assiniboine River crest is at the Spruce Woods Provincial Park and will reach Portage la Prairie later today or tomorrow. The Portage Diversion continues to be operated to maintain
1,200 cfs in the river heading toward Winnipeg. The flow in the diversion this morning was
5,600 cfs.
1,200 cfs in the river heading toward Winnipeg. The flow in the diversion this morning was
5,600 cfs.
· The river flow is much above average but is well within its bank at all points.
· The Shellmouth Reservoir water level has changed very little in recent days and stood at 428 m (1,404.26 ft.) this morning. The outflow will be maintained at 1,200 cfs until the reservoir level declines to 427.6 m (1,403 ft.).
Other Areas
· River levels are declining in the Interlake and on most streams in the Westman area. There is some flooding in the Nopiming Provincial Park.
· Levels of the Souris and Pembina rivers have risen somewhat due to last weekend’s rain but remain well within their banks.
· The Winnipeg River is still below average levels but is rising.
· The latest flood forecast, reports and other flood-related information is at www.manitoba.ca.
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