Manitobans who thought they had put their flooding woes behind them are being warned to brace again, as forecasters call for another major rain storm that could see the Assiniboine River breach its banks in the coming days.

If the rain falls as expected on Sunday or Monday, officials say water levels could return to the record heights that forced them to deliberately flood properties south of Portage la Prairie several weeks ago.

According to Manitoba Emergency Services Minister Steve Ashton, the looming storm, which would be the fifth to pound the region since the beginning of May, threatens to test province's flood defences.

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

But, even though the Canadian military's assistance was considered invaluable during the last flood threat, Ashton said they're not being called back to Manitoba just yet.

"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.

"Preliminary estimates show projected flows into the Portage Reservoir could reach 53,000 cubic feet per second (cfs) in the next seven to 10 days, with up to 34,000 cfs being directed down on the Portage Diversion channel and up to 19,000 cfs along the Assiniboine River dikes, depending on how much rain actually falls," 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.

More than 20 homes in the town of Souris were evacuated Friday, while others there were placed on evacuation alert.

Provincial officials say work has resumed to reinforce dikes along the Assiniboine River and on the Portage Diversion, as well as a number of communities around Lake Manitoba and Dauphin Lake.

Officials now expect Lake Manitoba to hit a high of 817 feet above sea level by mid-July.

With files from CTV Winnipeg and The Canadian Press