Wild rice sulfate standard
Officials: Too early to judge impact of enforcement
REGIONAL—Would enforcement of a new wild rice standard for sulfate discharges force cities and industrial users in the region to spend additional money to reduce the pollution they release into area lakes and streams?
That’s the contention of some Iron Range political leaders who have reacted aggressively to the possibility that the Minnesota Pollution Control Agency will continue to enforce the pollution rule. The rule dates back to 1973, but had rarely been enforced until recently.
The rule is currently under review by the MPCA, but initial scientific findings from the agency have determined that the regulation appears to be reasonable, given that high sulfate levels can, under certain circumstances, negatively impact the growth of wild rice.
Officials with the MPCA, however, say it’s too early to tell in many cases how the current pollution standard of 10 parts per million, or ppm, will affect either area mining operations or municipalities that operate wastewater treatment facilities.
That’s particularly true for many municipal wastewater facilities in the area, since the MPCA has not required small cities to test for sulfate discharges in most cases.
As existing municipal permits come up for review, (they require renewal every five years) they will likely include a requirement for sulfate testing, according to John Thomas, an enforcement official in the MPCA’s Duluth office. “Where we go from there would depend on the results of that testing,” he said.
Sulfate levels in municipal discharges can vary widely depending on the composition of municipal wastewater. Since 2010, the MPCA has required testing for the chemical in communities that have certain types of larger commercial or industrial operations that utilize municipal treatment, but in many smaller communities, that testing has not been required.
The Tower-Breitung wastewater system is a case in point. “We didn’t have Tower do that monitoring,” said Katrina Kessler, a permitting specialist with the MPCA.
The Tower-Breitung wastewater treatment system operates under a general permit that includes a number of municipalities that use stabilization ponds as a treatment method. The permit under which the Tower-Breitung system operates is up for renewal next year, and Kessler said the new permit would likely require that the municipal systems operating under it begin testing for sulfates.
“Monitoring data is the first step,” said Kessler.
The monitoring would likely continue for the five-year term of the permit. Once up for renewal in 2020, the MPCA would then have to consider a number of variables to determine if the wild rice standard for sulfate should be part of a new permit.
That determination, according to Kessler, is fraught with complication.
The first step in a multi-step determination process would be the easiest— does the discharge exceed the 10 ppm standard? If the answer is no, then a permit would likely only require continued monitoring.
If the answer is yes, then several other questions must be answered, including:
• Does the wastewater discharge into a wild rice water? That’s a difficult question to answer and it’s one that is likely going to result in much more debate, and possibly even litigation before it’s finally resolved. “It’s not inconceivable that you could have some municipal dischargers discharging into wild rice waters,” said Thomas.
A DNR map of known rice beds in the state indicates no known beds downstream of discharges from the Ely or Tower-Breitung wastewater systems. A wild rice bed is indicated on the map several miles downstream from Cook on the Littlefork River, as well as within Pelican Lake, near Orr.
• Is the discharge of sufficient volume in relation to the receiving waters to create a potential problem for wild rice? As Kessler points out, dilution is still a solution in many cases. That means that even if a city or industrial discharge is higher than 10 ppm, the volume of that discharge, and the volume of the receiving water, will be a consideration. For example, if a small city like Orr discharges into a large lake, such as Pelican, it matters less that the concentration of sulfates in the city’s discharge exceeds 10 ppm than if it were discharging into a smaller body of water.
• Does the chemistry of the receiving water mitigate the effects of high sulfate?
As MPCA research has determined, a number of factors can significantly mitigate the impact of sulfate levels above 10 ppm. In fact, the MPCA study determined that sulfate by itself is not harmful to wild rice. But the chemical, under certain conditions, is converted to hydrogen sulfide, which is harmful to wild rice and other aquatic plants. That conversion takes place under oxygen-free conditions, which are not always present in areas where wild rice grows. In those areas, higher sulfate discharges would likely not need to be regulated. Further, in the presence of relatively high levels of iron, the chemical process that creates the hydrogen sulfide is short-circuited, so where there’s high iron in the water, higher sulfate discharges may not be a problem.
“We now know it has more to do with other variables,” said Kessler. “The take home message is that we will be evaluating all new permits on a case-by-case basis. There’s no way to say that all municipalities will be getting new sulfate limits.” It will all depend, said Kessler, on the results of monitoring, whether wild rice is actually threatened, and other complicating factors.
Potential impact to mining industry
One of those watching the issue closely is Chris Vreeland, of Hoyt Lakes. Vreeland was the longtime Public Works Director for the city of Aurora and currently serves on the Hoyt Lakes City Council. He’s a supporter of the proposed PolyMet mining operation as well as Mesabi Nugget, and he’s concerned that enforcement of the sulfate limits could prove expensive for the mining operations, particularly Mesabi Nugget. PolyMet officials have already indicated that they intend to meet the state’s wild rice standard.
But Mesabi Nugget, which converts taconite into direct reduced iron pellets, has run into trouble as a result of sulfate discharge that’s closer to 150 ppm. The MPCA and the federal Environmental Pollution Control Agency had approved a variance for the company, but that variance was rescinded after it was challenged in court by Indian tribes and environmental groups. The company had proposed to store the high sulfate water during the summer growing season and discharge in the fall and winter, but opponents argued that the sulfate builds up in the environment over time.
Vreeland said the only effective way for industrial dischargers, like Mesabi Nugget, or for small cities, like Aurora, to reduce sulfate discharges is through reverse osmosis, which is expensive to build and operate. “For the city of Aurora, it could cost $2 million to set up,” said Vreeland. And operational costs are high in part because disposal of the highly concentrated brine produced by reverse osmosis is expensive.
The impact on existing taconite mining operations is also unclear, since the MPCA does not require them to test for sulfate in most cases. The only exception is the Keetac Mine, where the MPCA issued a new permit in 2011 that includes sulfate limits.
Most of the region’s other mines are operating under old, expired permits that did not require testing for the chemical, according to Kessler. It won’t be known for sure whether these plants are exceeding the sulfate standard until they actually begin testing for the substance.
Minntac’s expired permit does require monitoring, but sets no limits for sulfate discharge, and the company is discharging water from its tailings basin that is far in excess of the wild rice standard. “Back when these were issued, sulfates weren’t an issue,” said Kessler. The MPCA does have a current enforcement action against Minntac, as the company works to reduce its pollution discharges.
Vreeland said he’s not convinced that the current standard is even valid. He points to a study by the Minnesota Chamber of Commerce that found wild rice could withstand exposure to much higher concentrations of sulfate than 10 ppm, as much as 1,600 ppm.
“I think the jury is really out,” he said.
But John Pastor, a University of Minnesota-Duluth professor who was one of the lead researchers on the MPCA’s study, said the scientific data is clear and convincing. “The chamber of commerce report has no credibility— none,” said Pastor, in part because it didn’t look at how sulfate interacted within the lake sediments to create the hydrogen sulfide, which is what actually damages wild rice. “The sulfide is toxic to wild rice at very low levels,” said Pastor.
The chamber report is a critique of the findings of the MPCA research, and suggests that sulfate discharges could be as high as 1,600 parts per million without harming wild rice. The chamber used 1,600 because that was the highest concentration of sulfate examined in the MPCA study.
Pastor agrees that the sulfate, by itself, does not appear to harm wild rice germination or growth, but said that fact by itself does not tell the whole story.
Pastor said the suggestion by some Iron Range politicians to allow discharges of up to 1,600 ppm ignores both the science and the financial impact to downstream communities. Pastor notes that the current drinking water standard is 250 ppm, so allowing companies to discharge six times that amount into rivers or lakes would force communities relying on such polluted waters for drinking to spend significantly more to clean up the water before distributing it to residents. And, he noted, it’s usually cheaper to prevent water pollution in the first place than to clean it up afterwards.
While the sulfate standard was originally established to protect wild rice, Pastor said the benefits go beyond aiding the native grain. “Hydrogen sulfide is toxic to everything that breathes oxygen. Even if wild rice isn’t there, something else will be affected in the food chain, including fish. Wild rice is kind of the canary in the coal mine,” he said.