Most of the deaths occurred earlier in the 20th century [1]
As for the story in general ... it's not new information really. We have records of the deaths, families were notified, governments were notified, they didn't want to pay to ship the bodies so they buried them near the residences. We also knew where the graves were.
The Canadian government was aware at the time of the higher rate of deaths than normal, it was recognized as a problem, but obviously they didn't do much about it.
[0] https://www.statista.com/statistics/1041751/canada-all-time-...