Manitoba is bracing amid a fresh round of flood concerns as a storm forecast to reach the prairie province by Monday threatens to push the Assiniboine River over its banks again in the coming days.

The province is warning residents living outside Portage la Prairie that rainfall expected on Sunday or Monday could force the province to reopen a dike that had been used to control water levels during a previous flood threat.

The expected storm -- the fifth to pound the region since the beginning of May -- could push the Assiniboine River back up to the record heights that forced the province to deliberately flood the area south of Portage several weeks ago.

"As a result, the Manitoba government is reassessing all flood-protection measures at its disposal," the province said in a bulletin posted online.

The storm is expected to bring heavy rainfall to areas across southern Manitoba. Winnipeg, Steinbach, Morris and La du Bonnet are forecast to receive up to 70 millimetres of precipitation between June 12 and 15.

Forecasts suggest as much as 30 millimetres of rain could fall on the Souris and Assiniboine River basins next week. The region received as much as 300 per cent of its normal precipitation levels last month.

The Town of Souris has already declared a state of local emergency due to rising water levels. More than 20 homes in the town of Souris were evacuated Friday, while 17 others there were placed on evacuation alert.

Across the province there are currently 2,238 Manitobans evacuated from their homes.

The Canadian military -- which proved vital during the last flood threat -- will likely not be called back to assist this time around, Manitoba Emergency Services Minister Steve Ashton said.

"We're on a high state of alert again and our flood defences will clearly be pushed to the limit. We are already putting in place various initiatives to deal with that, but we will be watching very carefully over the next number of days because what does transpire with that major storm will once again challenge us in the province," Ashton told reporters in a flood briefing on Thursday.

As of June 9, the Portage Diversion was sending more than 30,000 cubic feet of water per second into Lake Manitoba. Flows into the Portage Diversion hit 52,300 cubic feet per second when officials chose to intentionally breach a dike at the Hoop and Holler Bend in early May.

Fearing an uncontrolled breach of the rising Assiniboine could have flooded more than 850 homes in an area covering some 500 square kilometres at the time, officials opted for an intentional release instead.

That move was expected to flood approximately 150 homes in a 225-square kilometre area. Ultimately, less than 4 square kilometres were affected.

But officials are now saying water levels could reach or even exceed those same levels again soon.

On May 18, the Assiniboine River crested at the Portage Reservoir at reach a peak of 52,300 cubic feet per second (cfs), before declinging to 18,480 cfs.

"As a result of the next forecast storm, flows into the Portage Reservoir are forecast to reach between 51,000 and 53,000 cfs, depending on future weather," the province warned.

Area residents who have yet to remove flood protection measures from their properties are now being told to reassess their effectiveness, while residents of 45 homes near the Portage Diversion have been told to be on evacuation alert.

With files from The Canadian Press