1960s mercury dump, CAN

A company dumped 20,000lb of mercury into Canadian rivers near an indigenous community. The mercury caused brain damage to the young people born subsequently in the community, which caused a high rate of brain damage and suicide.

I don't know if it is possible to punish today the company which did this in the 1960s. That may be too long ago. But is there any way to remove the mercury from the environment, to make it safe to live in?

If not, what can be done to prevent harm to future generations there?