June 4, 2010
Flood and Floodway Operations Update - June 4
Weather
· Manitoba Water Stewardship reports the present weather system produced 10 to 15 millimetres (0.4 to 0.6 inches) of rain in many areas of western Manitoba yesterday. Rainfall over the Red River Valley and the Interlake has been generally less than 5 mm (0.2 in.), significantly less than was expected. There is a chance of an afternoon shower today and some showers are expected Saturday. However, rainfall amounts from individual showers should be only in the five mm
(0.2 in.), range with total amounts of less than 15 mm (0.6 in.) from today through the weekend.
(0.2 in.), range with total amounts of less than 15 mm (0.6 in.) from today through the weekend.
Overland Flooding and Small Streams Update
· Overland flooding in areas hard hit by heavy rain last weekend continues to subside gradually. Areas of standing water are shrinking but are still significant. The present cool, damp weather is not conducive to rapid drying. Levels on streams in southern Manitoba are declining at virtually all locations and will continue to decline based on the current weather forecast.
Red River Floodway Operation
· The operation of the Red River Floodway that began at 6 p.m. Wednesday was to reduce the chances of sewer backup in Winnipeg from possible rainstorms during the month of June. Under this rule of operation, the floodway gatesmay beraised to maintain a level of 231.6 metres (760 feet) at the floodway inlet.
· Due to the reduced risk of heavy rainfall in Winnipeg, river levels upstream of the floodway will not be raised any further and will be maintained at 231 m (758 ft.) rather than 231.6 m (760 ft.) until further notice. The level at the inlet this morning was 231.1 m (758.24 ft.). The level will be raised to 213.6 m (760 ft.) only if a threat of heavy downpours develops for the Winnipeg area. With favourable weather conditions, river levels from the floodway inlet to St. Adolphe will begin to decline by mid June.
Red River
· Levels of the Red River declined 0.23 m (0.75 ft.) at Emerson and three in. (0.25 ft.) at St. Jean Baptiste during the 24-hour period ending this morning and the level was unchanged at Morris. Levels rose 0.21 m (0.7 ft.) at the floodway inlet, 0.27 m (0.9 ft.) at St. Adolphe and 0.39 m (1.3 ft.) at Ste. Agathe due to the operation of the floodway. Levels will decline from Emerson to Morris but will remain quite steady from Ste. Agathe to the floodway inlet for the next 10 days or so, based on no serious rainstorms developing.
· The river level in downtown Winnipeg declined 0.73 m (2.4 ft.) during the 24-hour period ending this morning, mainly due to floodway operation, and stood at 4.48 m (14.7 ft.) this morning. The level is expected to decline to about 3.96 m (13 ft.) by early next week and to near 2.7 m (nine ft.) by mid June based on favourable weather.
· The flow in the Red River Floodway this morning was measured at 12,200 cubic feet per second and the total flow at the floodway inlet was 43,450 cfs.
Assiniboine River
· The Assiniboine River crested at Portage la Prairie yesterday and continues to decline slowly at Baie St. Paul and Headingley due to operation of the Portage Diversion. The flow in the diversion was 5,355 cfs this morning and the flow at Southport was 1,200 cfs. Flows down the river toward Winnipeg will be kept at 1,200 cfs at least until the end of next week.
· The Shellmouth Reservoir water level rose 0.03 m (0.1 ft.) since yesterday and stood at 428 m (1,404.4 ft) this morning. Yesterday’s rainfall of 10 mm produced some additional run-off and has raised the inflow to 2,350 cfs. The reservoir level is now expected to rise to 428.2 m (1,405 ft.) by mid June. An outflow increase will be considered if significant additional rain develops during the next 10 days or so.
Other Areas
· River levels are declining in the Interlake and on most streams in the Westman area. There is some flooding in 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.
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