Condition Reports

River Conditions and Forecast for Manitoba

April 18, 2008

Weather:

The slow moving storm is expected to bring a mixture of rain and snow to eastern Saskatchewan and rain to western Manitoba Sunday to Monday according to the Environment Canada forecast. Precipitation amounts are not yet certain but it appears that 25 mm could fall in the upper Assiniboine, Swan River and Red Deer River Watersheds and the Duck and Porcupine Mountain areas. Rainfall amounts in the eastern half of Manitoba including the Interlake on Monday should be only about 5-10 mm range.

Red River:

Levels are declining at all points in Manitoba. The river level in downtown Winnipeg was 9.5 feet this morning and should decline below the Forks walkway level of 9 feet by early tomorrow.

Assiniboine River:

The Assiniboine River crest is still in the Virden and should pass through Brandon early next week. Crests from Portage La Prairie to Lido Plage are likely to occur during today or tomorrow as the remaining ice moves out. Peaks stages will be lower than in recent years and flooding is not anticipated along the entire length of the river unless precipitation from the coming storm is heavier than expected.

The Shellmouth Reservoir water level rose more than one foot during the 24 hour period ending this morning as inflows to the reservoir are now near the peak. The level of 1396.9 feet this morning is 11.5 feet below the spillway. An updated forecast based on little additional precipitation indicates that the level will rise to the desired level of 1403-1404 feet by early May but this will require outflows to be increased. The outflow will be increased to 800 cubic feet per second today. A further increase to 1200 cfs may be required next Monday, especially if the storm precipitation falls as expected. A forecast and operating plan will be presented to the Regulation Liaison Committee later today and again on Monday to facilitate decisions on outflow settings. At the present time it appears that the Assiniboine River will remain within its banks even with the storm. It is unlikely that crests from Miniota to Winnipeg, which have occurred recently or are expected during the next few days, will be exceeded later due to the storm.

Interlake Region:

The crest of the Fisher River was a Koostatak this morning and levels had declined significantly at all other locations. The level at The Peguis Townsite has decline one foot since yesterday. The risk of flooding is over and it is very unlikely that precipitation from the coming storm will cause any rises on the river.

Riding, Duck and Porcupine Mountain areas:

Levels continue to decline and all streams are within their banks. Rainfall expected Sunday to Monday is likely to cause some rises but all streams are expected to remain well within their banks.

The Pas area:

Runoff is underway but crest will be delayed by anticipated very cool weather next week. The Saskatchewan Watershed Authority indicates that peak flows in the headwaters of the Red Deer River and the Carrot River are one-half to two thirds the magnitude of last years crests. These rivers are expected to remain within their banks in Manitoba unless heavy precipitation develops during the next few weeks. Also inflows to Tobin Reservoir are expected to be about half the magnitude of last spring, and therefore flooding is not anticipated in the vicinity of The Pas.

Hydrologic Forecast Centre
Regulatory and Operational Services,
Manitoba Water Stewardship