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Tippy Thompson (left) and Jared Ward paddle their canoe through a dense growth of wild rice on Perch Lake near Sawyer in September 2013. While Thompson paddles, Ward uses wooden sticks called “knockers” to knock wild rice off the stalks into the bottom of the canoe. Forum News Service file photo

Scientists critique Minnesota wild rice study

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News Bemidji,Minnesota 56619
Bemidji Pioneer
Scientists critique Minnesota wild rice study
Bemidji Minnesota P.O. Box 455 56619

John Myers

Forum News Service

ST. PAUL — A panel of seven scientists from the U.S., Canada and Europe is taking a critical look at Minnesota’s recent research into how sulfate may damage wild rice.


The peer review panel was called to St. Paul by the Minnesota Pollution Control Agency this week to critique the state’s two-year, $1.5 million study on the impact of sulfate on wild rice.

The panel’s report could have a major impact on current and future mining in the state as the PCA, under legislative mandate, decides whether the state’s current 10 parts per million limit for sulfate is needed in wild rice waters.

“This scientific peer review is the next step in the PCA’s ongoing efforts to improve its scientific understanding of the effects of sulfate on wild rice, and to provide additional factual information for the PCA’s decision about whether the current Minnesota wild rice sulfate water quality standard should be changed,” the agency said in announcing the peer review meeting.

The PCA contracted with Eastern Research Group Inc. to find scientists with expertise on sulfate impacts on plants. The panel includes Donald Axelrad of Florida A&M University, Patrick Brezonik of the University of Minnesota, Siobhan Fennessy of Kenyon College, Susan Galatowitsch of the University of Minnesota, Mark Hanson of the University of Manitoba, Curtis Pollman of Florida-based Aqua Lux Lucis Inc., and Gertie Arts of Wageningen University and Research Centre, Netherlands.

The two days of meetings that ended Thursday were open to the public. The peer review panel heard questions and comments from interested parties Wednesday — including from tribal, environmental and business groups.

Sulfates are ions or salts that can come from decaying plants and animals as well as from some mineral deposits and industrial processes such as mine discharges, mine stockpiles and waste piles, tanneries, steel mills, pulp mills, sewage-treatment plants and textile plants.

From 2011 into 2013, University of Minnesota Duluth researchers studied sulfate’s impact on wild rice in both a laboratory and in large plastic tubs outdoors, while University of Minnesota Twin Cities scientists studied wild rice stands in dozens of lakes and rivers across the state.

In March the PCA released the preliminary findings of that research — essentially that sulfate above 4-16 parts per million can produce a chain reaction in the ecosystem that harms wild rice. When sulfate levels are that high or higher in the water around the roots of wild rice plants, they can spur the production of hydrogen sulfide, and that hydrogen sulfide can starve the plant of nutrients.

The report said wild rice generally suffers when hydrogen sulfide levels hit 150-350 parts per billion. Those levels began to occur when the surrounding water had sulfate starting at 4-16 parts per million, especially in waters with low iron concentrations, the report said.

But the PCA report stopped short of deciding whether the current, controversial statewide standard of 10 parts per million for sulfate pollution in wild rice waters should continue, go up or go down. PCA officials have said that it may be well into 2015 when the PCA issues a more definite finding on what changes to make, if any, to the wild rice rule.

Tribal and environmental groups say the science clearly shows the current standard is needed to protect wild rice from the indirect effects of sulfate. But business interests say the opposite, that the science shows sulfate is not a direct cause of harm and that no sulfate limit should be imposed. The Minnesota Chamber contends the state sulfate limit should be 1,600 parts per million, if any limit is needed at all.

Ultimately, even after the PCA decides on the sulfate issue, the federal Environmental Protection Agency will have to sign off on any change under the federal Clean Water Act.

The sulfate rule, if enforced, has huge implications for the state’s iron mining industry, with some taconite processing plants apparently releasing sulfate at levels above the current standard. It could affect the state’s fledgling copper mining industry as well as wastewater treatment plants in areas where wild rice grows, or did grow in the past. For example, the PolyMet copper mine proposed for northeastern Minnesota can meet the existing sulfate standard, an environmental review concludes, but only by treating water that leaves the site for years to come.

Still to come is perhaps an even more controversial decision by the PCA — precisely which lakes and rivers in Minnesota are official “wild rice waters.” That decision, which the PCA says will come after a so-called administrative rulemaking process in coming months, will decide where the sulfate standard will be enforced.

The PCA also must better define when the standard applies — all year or only during the growing season. The report released in March seems to show that the sulfate-to-hydrogen sulfide conversion can occur at all times of year, although less often in colder conditions.

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