List of impaired waters keeps growing in Minnesota

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Matt Doll, Minnesota Environmental Partnership

Earlier this week, the Minnesota Pollution Control Agency added more than 300 stretches of water to Minnesota’s impaired waters list. Each lake, stream, or river included on this list is considered to be impaired by failing to meet environmental standards for beneficial uses, including drinking water, aquatic habitat, fishing, or swimming. The pollutants causing these impairments vary, but they’ve added up to a disturbing fact: the majority of waters in Minnesota are now on that list.

Given the trends that MEP has closely followed for years, the continual increase in the impaired waters list is not surprising. In fact, the MPCA may be undercounting the waters that are impaired – recognizing that adding a body of water to the list can be a complex process that the agency and environmental groups work on for years. Even as some point sources of pollution like industrial facilities are shut down, new pollutants emerge. Currently, there is not an adequately regulatory framework to address them, so waters suffer more and more pollution.

Mercury is a classic example, and one of the largest sources of impairment in Minnesota waters. In the present day, Minnesota industries have greatly decreased the amount of mercury they release into the environment, though coal plants elsewhere in the country continue to deposit the toxic chemicals into our lakes, blown in on the wind. But there’s a significant amount of mercury in the river bottom in places like the St. Louis River estuary near Duluth.

As an MEP-commissioned report showed last year, industries like mining continue to release sulfate into the water. Sulfate reacts with mercury in the water to cause it to move up the food chain through fish and other aquatic life. This mercury bioaccumulates, meaning that it becomes more concentrated and more harmful the further up the food chain it goes, resulting in a health threat to humans who eat the fish. Sulfate also threatens production of wild rice, a significant problem especially for Ojibwe communities. The state has not yet adequately protected our waters from sulfate, but has begun recognizing sulfate concentrations that are dangerous to wild rice in its impaired waters list – especially after the EPA stepped in earlier this year.

PFOS is another emerging pollutant that is now being taken into account, resulting in the addition of 15 waters to the MPCA’s list. This forever chemical – a substance that does not break down naturally in the environment – is used in industry, firefighting, and consumer goods like Scotchguard. It has been recognized for years as a threat to humans and wildlife as a risk factor for kidney disease, cancers, and other conditions as our scientific understanding has evolved. Small amounts of PFOS are present in the blood of almost every person in the United States, though fortunately, concentrations have been decreasing over time. The lower St. Croix River between Minnesota and Wisconsin is one notable location deemed impaired due to PFOS contamination.

The EPA has announced that it will develop national drinking water standards for PFOS, while the European Union has banned almost all uses of it since 2006. It is no longer commonly produced in the United States. Minnesota has also passed a limited ban on PFOS’s fellow forever chemical, the cancer-causing chemical PFAS, in food packaging, and settled an $850 million lawsuit with 3M over the company’s pollution of East Metro water supplies. Pressure is building for companies to continue replacing and phasing out these forever chemicals.

Meanwhile, older and more widely-known pollutants continue to impair Minnesota’s waters, most visibly nutrient runoff in streams, rivers, and lakes. Vast swaths of waters in southern Minnesota are especially impaired by phosphorus. The primary source of this pollutant is from crop fertilizer, though sewage systems also play a role.

Excess phosphorus fertilizer spread on crops ends up running off of farm fields and into lakes and rivers, where it causes algal blooms. These algae decay, consuming the oxygen in the aquatic habitat and rendering it inhospitable for fish and other life. These blooms can also result in bacteria that are harmful or even deadly to people and wildlife.

Fortunately, fertilizer pollution is a problem with known solutions. By introducing “clean water crops” and cover crops to farmland, phosphorus use can be reduced and mitigated, protecting the waters downstream and maintaining the health of the soil. Employed in the right areas, these and other techniques can go a long way toward healing Minnesota waterways.

Minnesota’s “Land of 10,000 Lakes” nickname and our position at the headwaters of the Mississippi and Lake Superior mean that what happens here flows downstream. We have a responsibility to treat our impaired waters list as a call to action, not just as a tally of disappointments.

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