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How polluted is the river now?
State and federal officials say that the spike of toxins lasted about eight hours. Since then, the EPA has built four collection ponds at the mine site, where it is treating the water in order to reduce acidity levels and remove dissolved metals. Officials say the pollutants have now dissipated to the point that the river near the spill point is returning to normal water-quality levels — and is regaining its greenish-blue hue. But the contaminants will eventually settle in the river bed, and could be kicked back up during rainstorms.
How long will the pollution stick around?
Jeff Curtis, a University of British Columbia scientist and water quality expert, said he expected two waves of toxins to move downstream from the spill. The first wave comprises water-soluble pollutants, including arsenic and cadmium, freely flowing with the river's current. The second wave of less soluble materials, including lead, will settle in river basin sediment and be churned up by later rainstorms.
That means that the full impact of the spill will take years, perhaps decades to unfold, as the toxins continue to move through the ecosystem. Fish will bear the brunt of the contamination, poisons slowly accumulating in their bodies.
The effect on humans will take much longer to measure, Curtis said.
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http://www.nbcnews.com/news/us-news/week-after-toxic-river-spill-impact-west-remains-unclear-n407896
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