Thirty-six communities in Saskatchewan and 31 municipalities Manitoba are under states of emergency because a deluge of heavy rain has caused flooding.
The Red River Floodway will begin operating Tuesday to divert water around Winnipeg.
The Portage diversion, a channel that funnels water from the Assiniboine River into Lake Manitoba, is also being used.
Rainfall has led to flooding and record flow levels on 13 southern Manitoba rivers and streams.
Officials in Manitoba and Saskatchewan both say some land was already saturated and the latest rain has turned swollen creeks into raging rivers.
About 200 people in Manitoba and more than 300 in southeast Saskatchewan have had to leave their homes because of rising water levels.