Changing the protection of wild rice waters: What you need to know

In a move that could have an impact on mining in northeastern Minnesota, the state started taking public comment this week on a proposal to change the way it protects waters where wild rice grows.

The state has had a law on the books since the 1970s limiting how much sulfate can be discharged into wild rice waters, but that law has come under increasing scrutiny in recent years from business groups, state legislators and others.

Here's what you should know about the law and potential changes.

What is the origin of the wild rice standard?

A biologist named John Moyle sampled lakes and rivers around the state in the 1930s and '40s. He found that wild rice did not grow well when the water had high concentrations of sulfate. Because wild rice is such a cultural touchstone here, being the state grain and very important to tribes, the state adopted a standard in 1973.

How is the proposed new standard different from the current one?

The current standard limits the amount of sulfate in water where wild rice grows to 10 milligrams per liter. That translates to about seven gallons in an Olympic-sized swimming pool.

The new rule would replace that broad standard with a formula that figures out how much sulfate is safe for wild rice in each specific water body. It would be a more flexible standard.

Why is the MPCA proposing this change?

The agency says the current standard is too rigid. It says in some lakes, wild rice can grow with a lot more sulfate than 10 parts per million. But in other lakes, it may not be able to tolerate even that much.

That's because it's not actually the sulfate that harms the wild rice. When that sulfate mixes with bacteria in the muck at the bottom of lakes, it converts into sulfide, which is toxic to wild rice plants.

But recent research has shown that naturally occurring iron and organic carbon that are also in that muck play a role in how readily that sulfate is converted to sulfide.

Under this new proposal, researchers would sample the sediment in a specific water body, find out how much carbon and iron is there, and then plug that into a formula to figure out how much sulfate is safe for wild rice.

How would this affect the mining industry?

Sulfate occurs naturally, but it's also released by mining operations and other industries. There are also a lot of wild rice waters downstream from mines on the Iron Range, so this rule potentially could have a big impact up in northeast Minnesota.

It was actually the industry that pushed the state to scrutinize the old standard and come up with an alternative. The reaction from mining interests and the Iron Range delegation to the proposed change has been generally positive.

Who are the critics and what are their concerns?

Environmental groups have said a flexible standard could create openings for political pressure.

John Pastor, who's a biologist at University of Minnesota Duluth, has been critical. He did much of the research for the MPCA's recent study that analyzed the old 10 parts per million standard.

Pastor says the MPCA hasn't shown the formula it's proposing can accurately predict a safe level of sulfate.

He also says that to get an accurate measure of the iron and organic material in the sediment, the MPCA would have to collect up to a hundred different sediment cores in just one lake. Pastor says those conditions in the sediment in any given lake can change from year to year.

The MPCA says it is investigating those issues and how exactly the new change would be implemented.

What does Pastor propose?

He says his research showed that the old, 10 parts per million standard will protect wild rice 80 percent of the time. He thinks it should remain in place. The MPCA has said that standard isn't wrong, it's just imprecise.

What happens next?

This issue is far from settled. The proposal is now open for comment until Dec 18. Ultimately, the federal Environmental Protection Agency would have to sign off on any change Minnesota makes to its wild rice sulfate standard. The MPCA estimates a new rule wouldn't go into effect until January 2018.

Clarification (Oct. 27, 2015): A previous version of this story said the Legislature adopted a sulfate standard for wild rice waters in 1973. The state adopted the standard without legislative action.