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Image of wild rice in canning jars.

Wild Rice Under the Microscope

Scientists work fast to learn what sulfate does to Minnesota's iconic natural food.

by John Myers

University of Minnesota researchers have been working with hula hoops, canning jars, and plastic tubs for the past two years in a painstaking effort to measure the impact of sulfate pollution on wild rice.

Their research could help determine why Minnesota's famed wild-rice stands seem to be declining. And the results could help plot the future of the state's taconite iron-ore mining industry and the beginning of copper and nickel mining in Minnesota. By some estimates, the state may hold the largest untapped deposits of copper, nickel, and related metals in the world.

The study is under way to better understand the relationship between sulfate and wild rice. Sulfate is an ion containing sulfur and oxygen. Sulfate comes from natural processes, such as decaying plants and animals, and from industrial processes of tanneries, steel mills, pulp mills, textile plants, and wastewater treatment plants. Sulfate can even fall from the sky in the form of acid rain. In northeastern Minnesota, data from some state-permitted iron mining and ore processing facilities, which are subject to monitoring, indicate elevated levels of sulfate that may be affecting wild-rice growth downstream.

Research in the 1940s by John Moyle, a scientist for the Minnesota Department of Conservation (now called the Department of Natural Resources), showed wild rice was seldom found in waters with high sulfate.

"Moyle did a great job documenting the correlation between sulfate and wild rice in the 1940s," says John Pastor, scientist at the University of Minnesota Duluth. "But he didn't take it as far as proving sulfate caused wild rice to decline. We're trying to find out if sulfate really is the limiting factor and, if so, what it's actually doing to the rice."

Looking at Roots. Pastor and his crews are using canning jars with special airtight lids to grow wild rice in liquid solution, or hydroponically, to test the reaction to sulfate and other variables. Inside Pastor's lab, wild-rice plants grow in chambers under lamps that mimic the long days of a northern Minnesota summer.

At the university's outdoor field station, Pastor is using plastic tubs, simulating 30 little lakes exposed to all the elements of north woods weather. For the past eight years, in a project supported by the National Science Foundation and the Fond du Lac Band of Ojibwe, Pastor had been using the tubs to study which nutrients are key to growth of wild rice. Now he's using the tubs to see how sulfate affects rice.

Meanwhile, Amy Myrbo, a limnogeologist at the university's Twin Cities campus, has used hula hoops to measure rice density. For the past two summers, crews in canoes have used these handy, uniform circles at more than 130 sites in lakes and rivers across the state. The crews took samples of water sucked from sediment around roots, sediment-core samples, and measurements of nutrients and water chemistry. If they found no rice where historical reports hint there should have been rice, they looked for plants such as lilypads that grow in similar conditions and took readings there.

During fieldwork in 2011 and 2012, the researchers collected data that seemed to buttress John Moyle's findings: Wild rice was not abundant in water with more than 10 parts per million sulfate.

"In waters with high sulfate, we've struggled to find any wild rice," Myrbo says of the latest research, all of which is being overseen by the Minnesota Pollution Control Agency.

So far researchers have sampled a limited number of waters with sulfate levels higher than 10 parts per million, but the PCA plans to examine more of them in 2013.

Pastor and other scientists say the damage to wild rice probably occurs when sulfate is converted to hydrogen sulfide. In an oxygen-starved environment such as the sediment under wild-rice beds, bacteria "breathe in" sulfate and "exhale" hydrogen sulfide, which can be toxic to plants, says Ed Swain, the PCA research scientist who is coordinating the wild-rice research project.

Pastor knows from previous research that the availability of adequate nitrogen is the biggest limiting factor for the growth of wild rice. Now he is seeing wild-rice plants exposed to high sulfate that "didn't look poisoned. They looked starved." Pastor's hypothesis is that sulfate transformed to sulfides is affecting root growth and blocking nutrients from getting into plants. Now he will see if the research supports his hypothesis.

Scientists also will look at the role of iron in the sulfate-to-sulfide conversion and how sulfate can reduce the iron, copper, and zinc available to plants.

"You don't just throw in sulfate and the plant dies," Pastor says. "It's a whole ecosystem reaction that happens over years."

Changing Rules. Minnesota has had a rule on the books since 1973 limiting the amount of sulfate in waters used for the production of wild rice. That's when the state adopted Moyle's observation as it set a sulfate standard to protect wild rice, one of many water-quality protection measures under the then new federal Clean Water Act. The rule went mostly unknown and unenforced until, in recent years, environmental and tribal groups pressed the PCA to enforce the sulfate limit in mining permits to protect what appear to be dwindling stands of wild rice downstream from mining operations.

Mining industry officials, many northern lawmakers, and the Minnesota Chamber of Commerce are battling back, saying the sulfate limit could put taconite plants out of business and could prevent copper-nickel mining from becoming a huge industry here. The chamber filed a lawsuit in 2010 challenging the 1973 standard as arbitrary, unfounded, and too restrictive for the mining industry. The chamber lost at both the district court and the appeals court levels.

State lawmakers in 2011 moved to change the wild-rice standard, with bills passing committees to raise the standard to 50 and even 250 parts per million. Ultimately, the effort stopped short of becoming law after the federal Environmental Protection Agency signaled it would reject any legislatively imposed standard without science to back up the move.

And that's where the wild-rice sulfate study comes in.

Many copper-nickel mining projects are on the drawing board in Minnesota, with the potential to create thousands of jobs and generate millions of dollars. With this in mind, Minnesota lawmakers in 2011 gave the PCA $1.5 million and just two years to find the answers. The PCA, using data from the study, will decide what the sulfate limit should be, which lakes and rivers will be considered "waters used for the production of wild rice," and whether the limit applies only in the growing season or year-round.

What is known is that sulfate levels have gone way up in some areas. Historic, or background, sulfate levels in northeastern Minnesota waters were generally low, well below 10 parts per million. Now, downstream of the Iron Range after a century of mining activity, levels on some waters can approach 100 parts per million or higher.

Other Factors. No one suggests that sulfate is the only thing harming wild rice. A warming climate, more floods and droughts, shoreline development, and a host of water-quality issues probably are contributing to the problem of dwindling wild-rice stands. The decline of wild rice is likely affecting how waterfowl use Minnesota lakes, because wild rice is a key food during fall migration. The decline also may be one reason fewer people are harvesting this tasty natural food. DNR records show license sales for harvesting wild rice peaked at about 16,000 in 1968 and have plummeted to just 1,500 annually.

Many Ojibwe people regard wild rice—manoomin—as a sacred gift from the Creator. Ojibwe harvesters say they too have seen the decline in the stands across the region where their ancestors settled precisely because wild rice was so abundant.

"We've been on a downward spiral for a long, long time with wild rice," says Robert Shimek, a Red Lake Ojibwe, wild-rice harvester, and member of the PCA sulfate-study advisory committee. "We're seeing less and less wild rice for each generation."

Which Waters? Deciding which waters are wild-rice waters isn't going to be easy. A 2008 DNR report lists 1,286 Minnesota lakes and rivers as wild-rice waters. That's fewer than the state held historically, says Ann Geisen, DNR wildlife lakes specialist and a member of the PCA sulfate-study advisory committee. However, the lack of data prior to 2008 makes it difficult to quantify how many wild-rice waters have been lost.

The PCA's 32-member committee includes representatives of taconite companies, business groups, environmental groups, Indian resource agencies, and research universities. So far there's little consensus among them on whether wild rice must be growing in a place to be considered a wild-rice water for the sulfate rule or whether some past presence of wild rice is enough.

"You have to set some realistic criteria to set rules like this, or I can guarantee you will shut down every bit of economic growth in this state," said committee member David Skolasinski at a January meeting of the group. Skolasinski is district manager of environmental planning and analysis for Cliffs Natural Resources, which operates three taconite plants in Minnesota. "There has to be balance between protecting wild rice and letting people live their lives," he said.

Accurately defining wild-rice waters is critical, says Paula Maccabee, another committee member and attorney for the environmental group Water Legacy. "If a lake or river doesn't make the list, it doesn't get any protection under the wild-rice sulfate standard," she says. "That means dischargers can contribute a whole bunch more sulfate and not be in violation of anything." The list should be broad and flexible, Maccabee says, with lakes and rivers added if they are found to hold stands of rice: "The DNR's survey should be just a start. Especially with rivers, we know there are a lot more wild-rice waters out there."

The PCA is expected to receive a research report by year's end and make a decision on the 10 parts per million rule in early 2014, says Shannon Lotthammer, director of the PCA Environmental Analysis and Outcomes Division. If the PCA decides a change is warranted, an administrative rulemaking process would begin that would take several months and invite public comments. The change also would require EPA approval. This would likely take well into 2015, according to a PCA timeline.

If the PCA determines a change in the sulfate standard isn't warranted, or if a revised standard is proposed by the PCA but not approved by the EPA, the 1973 standard will stand.

Mike Robertson, an environmental consultant for the Minnesota Chamber of Commerce and a member of the advisory committee, says he hopes the PCA can make its ruling on time. But he conceded that the study was running slower than expected, with more questions emerging as more research comes in. Robertson and others say more time or money might be needed for another year or more of research.

"We support the PCA's original timeline. But we also want the science to be done right," Robertson says. "There is some urgency needed here. We have members waiting to get permits to create jobs in Minnesota that are really being held captive by this [sulfate] limit that may or may not have any validity."

Reducing Sulfate. Even as the state's wild-rice research began, PolyMet Mining Co. was trying to develop a way to get sulfate out of mining wastewater. PolyMet, the first company to seek permits to mine copper in Minnesota, has been reworking its plans the past few years to gain state and federal approval. The company has pledged it will meet the state standard.

This past October PolyMet officials announced they had successfully tested a reverse-osmosis treatment system that removes sulfate from water to meet the current standard.

Some say the same system could be used at taconite plants, wastewater treatment plants, and other sources of high sulfate. But the technology isn't cheap and could add millions of dollars to the cost of any facility. And it's not clear how much of the sulfate leaving a mining operation would be captured.

Pastor says he's never seen so much interest in one of his investigations. "I've been involved in a lot of controversial work before. But not even climate change was as controversial or as political as this. This is one plant and one substance and for the most part one industry. It's all so focused. There's a lot at stake here."

The scientist says researchers are under the gun to do good science, fast, while the PCA must then make big decisions fast.

"It's not the perfect way to do science, to put that end date out there and draw a line," Pastor says. "But we'll make it work. We may not answer all of the questions, but we'll know more about sulfate and wild rice than anyone has known before."


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