The 1.25-mile-long ice jam north of Winnipeg pushed the water levels in Selkirk up more than 2 feet in a few days, The Canadian Broadcasting Corp. reported.
Selkirk Mayor David Bell told the CBC that he saw the manager of the Selkirk marine museum dealing Wednesday with a trickle from a small break in a dike.
"The next thing you know it was like, 'Let's just get our stuff and get out of here,' and within an hour and a half, the boats that were dry were pretty much floating," he told the CBC.
Problems at the sewage treatment plant caused by the flooding forced workers there to pump sewage into the river.
The mayor said it will probably be Sunday before evacuated residents can return and some will find their basements have been flooded.