Babies on the North Shore had mercury in their blood. Too much mercury.

In late 2011, the Minnesota Department of Health released a study about levels of mercury in the blood of infants born in the Lake Superior watershed. The study showed that 10% of the infants in the Minnesota portion of the watershed had mercury levels that exceeded health limits. Nearly 120 babies from around the Lake Superior shore faced uncertain futures due to a contaminant their mothers had ingested and passed on to them.

Unlike many scientific studies that disappear into academic journals, this one triggered an immediate wave of concern as well as a remarkable follow-up program. The media were quick to pick up the story.

The Minnesota Department of Health doesn’t just do research, however. It takes action. Funded by a grant from the Great Lakes Restoration Initiative and collaborating with health clinics in Grand Marais and Grand Portage, state health department officials kicked off the Fish are Important to Superior Health (FISH) project.

Women of childbearing age along the North Shore provided blood samples and shared how much fish they normally included in their diets. While walleyes are higher in mercury, other local wild-caught fish are lower in mercury, and participants learned about how to choose the right fish to eat. Follow-up studies showed that in general the participants reduced the amount of mercury in their blood.

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But reducing the level of mercury in your diet is not the same as reducing the level of mercury in the environment.

Sadly, mercury levels in the environment do not appear to be going down. The St. Louis River is the largest tributary to Lake Superior on the U.S. side. It’s been known for decades that the St. Louis River contains too much mercury. Anglers along the river are warned to limit their consumption of fish from the river, primarily because of the mercury.

If you live in West Duluth or Morgan Park and you’d like to catch some crappies to feed your family, be careful: The Minnesota Department of Health recommends no more than one meal per month from the St. Louis for children or women of child-bearing age, due to the mercury contamination in the tissue of fish.

The mercury in the St. Louis River comes from many sources. Recent studies have shown that mercury from decades ago is reemerging from sediments at the bottom of the river and entering the food chain. Taconite and electricity plants in Northeastern Minnesota continue to emit mercury into the air, and it falls into the headwaters of the St. Louis River just downwind. Sulfate pollution from the same sources reacts with the mercury and creates methylmercury, the form that fish (and babies) take up. Proposed new mines could add more mercury and more sulfates.

But just because the sources of mercury in the river are complicated, it doesn’t mean we can’t do anything about it. The good news is that we have a path forward to address this issue. State agencies are stepping up to act.

Thanks to the Clean Water Act, governments are required to address impairments in water quality. This process starts by determining how much mercury is entering the river and where it’s coming from. This process is known as a Total Maximum Daily Load study, or TMDL study.

In the next few months, the Minnesota Pollution Control Agency will be restarting its long-awaited TMDL study of mercury in the St. Louis River. This could finally lead to long-overdue permit restrictions on mercury emissions, along with guidance on related environmental chemicals like sulfates. The Minnesota Environmental Partnership is urging the MPCA to do this work right and to engage the communities and local knowledge along the river.

The infants’ blood told us what we suspected, that there is too much mercury in the St. Louis River. Mercury from local sources — from taconite plants to municipal sewage plants — needs to be reduced. And we should never add new sources of mercury in the watershed.

The babies in that original study are now 10 to 12 years old and are finishing up elementary school. Wouldn’t it be great to tell them now that they live in a cleaner world, that mercury in Lake Superior and its tributaries has come down, and that they can eat all the crappies they can catch?

We’re not there yet. Let’s tell them this: If we can do the St. Louis River mercury TMDL right, we’ll be on the right path to getting there.

Andrew Slade of Duluth is the Great Lakes program director for Minnesota Environmental Partnership (, a nonprofit based in St. Paul.