The $950-million class-action suit claims the government was negligent in its operation of a number of water-control structures, including the Shellmouth Dam and the Portage Diversion.
The suit alleges the government caused excessive flooding in the communities of Dauphin River, Little Saskatchewan, Pinaymootang (Fairford), and Lake St. Martin.
Documents were filed this week in court.
The flooding on the four First Nations caused the displacement and relocation of hundreds of people.
"They shouldn't have diverted the waters. They should have exercised better forecasting and better flood control,” said Bill Jenkins, one of the lawyers for the communities.
“And once they evacuated the people from the reserve they should have provided better accommodation and care."