Flood watch issued in Manitoba

Heavy rainsdumped byrolling thunderstorms have prompted Manitoba Water Stewardshipto issue aflood watch for mostof southern Manitoba.

Flash flooding has already occurred in areas along the La Salle River and Seine River watersheds due to astorm system that brought 50 to 70 millimetresof rain to those areasFriday.

Many other areas of Manitoba received 20 to 30 millimetresof rain in that same time, but as much as 70 milimetres more could fallalong the Red River Valley fromEmerson to Winnipeg and across southeastern Manitoba through the weekend, according to a news release issued by the watershed authority (MWS).

In Winnipeg, 30 milimetres has already fallen and 40 to 50 milimetres more could come by Sunday, CBC News meterologist John Sauder said.

Soil saturated

The rain is falling on soil alreadysaturated from heavy rain on the Victoria Day long weekend. As a result,overland flooding is likelyaroundditches and smaller streamsthat are unable to take in anymore water.

The level of the Red River is also rising quite rapidly due to downpours in the United States last weekend, theMWS said. Itwill remain within its banks unless additional heavy rain develops in early June.

High river levels in Winnipeg impact thecity sewer system's ability to operate at a normal capacity. That means there is an increased risk of basement flooding asthe overloaded system backs up through household sewer lines that aren't protected by sump pumps and backwater valves.

Floodway operation considered

"In accordance with the Red River Floodway's rules of operation, Manitoba Water Stewardship will complete an assessment of whether operation of the floodway is necessary to prevent widespread basement flooding in Winnipeg if the rain this weekend results in a river level forecast above 4.3 metres," states the MWS release.

The river level in downtown Winnipeg Friday was at 3.4 metres and could crest at about 4.9 metres by June 5 with therain forecasted over the next few days.

Flooding is not expected along the Assiniboine River, however a decision on whether to operate the Portage Diversion to lower river levels in Winnipeg will be made in the next few days.

Thediversion redirects some of the flow of water in the Assiniboine to a 29-kilometre long diversion channel that empties into Lake Manitoba.

Most tributaries of the Red, Assiniboine and Souris rivers are expected to remain within their banks but some over-bank flooding of low-lying areas is possible, MWS said.

The latest information on water levels and outlook reports is available on the Manitoba government website at the top right of this page.