Buried Sediments From Long-Gone Mining & Industrial Operations Pose Long-Term Great Lakes Threat

Nickle Beach, Copper Harbor, Silver Bay. These places, all situated on the shores of the Laurentian Great Lakes, evoke the legacy of mining connected with the region. While mining operations for metal ores and their refining have all but ceased here, there are renewed concerns over the safety of our Great Lakes source waters. One only has to think back to the 2014 water crisis in Flint, Mich. that exposed more than 100,000 people to elevated lead levels or to more recent headlines over lead contamination in water distributed from Canadian taps.

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Clearly, past environmental crises like mercury pollution of Lake St. Clair in the 1970s, the St. Clair River’s blob of perchloroethylene (a dry-cleaning solvent) in 1985, the outbreak of gastroenteritis in Walkerton, Ont. in 2000, the contamination of Michigan’s Huron River with PFAS (a family of persistent chemicals) in 2017, and the Flint water crisis provide compelling evidence of the need to control contaminants at their source and avoid another tipping point.

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While the remaining industrial activity on the Great Lakes is regulated, the lakes themselves contain reservoirs of legacy contaminants, mostly in their sediments, that are vulnerable to resuspension. Metals, including mercury, PCBs and other persistent organic compounds top the list of concern. Resuspension is becoming more common under climate change with high water levels, declining ice cover and increased frequency and intensity of major storm events.

In fact, the manifestations of climate change in the region may be placing our drinking water systems at risk from a myriad of threats. These concerns include antibiotic-resistant bacteria, threats from emerging chemicals, increases in discharge from combined sewer overflows and enhanced agricultural runoff of fertilizers and manure, which are implicated in the massive harmful algal blooms that have plagued Lake Erie’s western basin in recent decades.

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https://theconversation.com/great-lakes-waters-at-risk-from-buried-contaminants-and-new-threats-128992