Cyanide is a very powerfull poison so small concentrations are problematic. But there are less strong ones that in larger concentrations or volumes are just as problematic.
As examples, a while back I had an curiosity in a mine in Hungary ( eastern Europs's lack of regulations and control) which polluted a river ( arsenic if memory serves ) flowing into Austria.
More recently due to an interest in Venezuela ( potential mines confiscated by government) was an issue of illegals using mercury to extract gold and then there is a large copper resource that a company had no intention of extracting but leaving it in the tailings. Copper is a low grade poison to the environment.

Hoov do you have some knowledge as to how the contamination occured at Attawapiskat? I may be of interest to us as to how in a supposedly well managed country such occurs, I definitely am.
I am not far from Walkerton, southern Ontario, where cattle fecal? contamination occured in a town's water supply due to poor management.

I know it is early to be discussing tailing ponds and permitting process for us but we all need to be cognizant of the potential problems so that if they do occur we do not become discouraged to quickly.

In is a slow time on the forum so we could be engaged in somewhat off topic discussions.

All problems are avoidable and if not, most have practical solutions. Politics and exaggerated environmentals trump all unfortunately, so we need to know ahead of time what is valid and appropriate.