Sure, mercury is scary, and I wouldn't want to eat the stuff on a regular basis, but this article is a hit piece at worse or an ignorant rant at best.
The problem is that it's easy to blame mining for the present level of mercury in the water, but since there is no benchmark level established prior to mining, the best we can say is that that it is not a good thing.
Knowledge of the hydrologic cycle confirms that percolation has always been with us and all that water eventually is subject to human use. It is silly to assert that the tailing of mercury ore is more polluting than mercury ore in its natural site.
Just like the asbestos panic ignores the profusion of serpentine exposed at the surface all over San Francisco.
The fact that measurement instruments have become sensitive to the point of absurdity does not validate the notion that the danger to humans has increased proportionally.