A Thunder Bay law firm now plans to sue the province over Thunder Bay's flooding, and is putting the Ontario government on notice Monday.

Sandy Zaitzeff of Watkins Law said the province is the regulator, and it failed to do its duty to monitor the city's systems and actions and to issue needed work orders.

"The province failed to alert the city that they must monitor storms as they track in and out of Thunder Bay ... to implement a disaster plan along with the city ... and to monitor a disaster plan, if it exists, which I don't know yet," Zaitzeff said.

The firm will file a $500 million class action claim against the Ministry of Environment, in addition to its bid for a $300-million class-action suit alleging the city was negligent.

"That claim will backstop the little city," Zaitzeff said.

"The province has the deepest pockets of all. I will not let this claim bankrupt the city. We will go after the province."

He added the province has the authority to force the city to act properly and if, for instance, city administration failed to do something, the province is accountable.

"They are the policemen and the cop on the block who failed to do their duty," he said.

After the province is given notice today, Zaitzeff said he will have to wait 60 days to file the suit.