The province says that super sandbags are in store again for First Street and 18th Street in Brandon, as preparations get underway for a spring flood.
Flooding in Westman is expected to be worse than originally hoped — but not nearly as bad as two years ago.
Although the Assiniboine River and Souris River froze in the fall with below-normal levels, a very heavy spring snowfall combined with a late thaw have increased the risk of moderate to major flooding in the region.
Assiniboine River outlook
There is a risk of moderate to major flooding on the Assiniboine River due to normal to above-normal average soil moisture in the upper portions of the watershed and above-normal snow-water equivalent in most of the basin.
In the worst-case weather scenario, there would be major flooding of the Assiniboine Valley from Shellmouth to Brandon similar to those levels of 1974 but lower than those of major floods in 2011, 1995 and 1976.
Brandon flood protection works are higher than the predicted flows.
Souris River outlook
No matter the weather, above-average snows in North Dakota, Saskatchewan and southern Manitoba will cause flooding of the Souris River and its tributaries. The province says that flooding is likely to be minor to moderate.
Over-bank flows are likely to occur from the U.S. border to Hartney.
If the weather turns worse, moderate to major over-bank flooding — with peaks similar to 2009 — is expected from the U.S.-Manitoba border downstream up to the town of Souris.
The towns of Souris and Wawanesa should not expect over-bank flooding. The town of Melita has sufficient dike elevation to protect against these levels.
Snowfall was 200 per cent of normal in much of Manitoba, Saskatchewan and North Dakota this month, and cooler than normal temperatures have increased the depth to which soil remains frozen. Across southern Manitoba, soil is frozen to a depth of between 50 centimetres (1.5 feet) to more than 100 cm (three ft.), mainly due to prolonged periods of very cold temperatures. Frozen soil does not absorb meltwater as easily as thawed soils, and it can increase spring run-off and overland flooding.
The colder-than-normal temperatures will also cause a later spring melt, which increases the likelihood of a rapid melt. Cool temperatures later into the year also increase the likelihood that the melting snowpack and normal spring rains will occur at the same time.
While all these factors have increased the risk of flooding to moderate to major, conditions can change quickly and the outlook is still very dependent on weather conditions from now until the spring melt.
The Assiniboine River is high for this time of year due to controlled releases from the Shellmouth reservoir, which have brought the reservoir down to near-record low levels to accommodate potential high water flow from Saskatchewan's snowpack.
Critical locations along the 160 km of Assiniboine River dikes that were heavily damaged in the 2011 flood have been inspected and repaired. Provincial officials say they continue to work closely with the City of Brandon as work continues on a $20 million flood-mitigation program.
Under the current outlook, one row of super sandbags may need to be positioned at 18th and First streets. The recently completed eastern access roads will also provide alternatives when travelling in and around Brandon this spring in the event of significant flooding.
The province also has two million sandbags and sand, six sandbagging machines, 17,000 super sandbags, 43 km of Hesco cage barriers, 50 km of water-filled barriers, 61 heavy-duty steamers and 34 mobile pumps ready to deploy on an emergency basis.
The Manitoba government has hosted more than a dozen training sessions with municipal emergency management staff as well as regional pre-flood information sessions with officials in Brandon. The province will begin regular regional forecast reviews with municipalities as the spring melt begins.
Forecasters say this will be the final outlook, although daily flood reports will be issued beginning in April, during the time of active melt and river flow.