Based on continued analysis from sediment samples taken over a long period, and from a draft proposal received earlier, Minnesota Pollution Control Agency (MPCA) scientists are continuing to refine the proposed approach to protect wild rice from excess sulfate.
Currently the state has a 10-milligram per liter sulfate standard for wild rice, but MPCA has proposed to eliminate that and is planning to recommend different standards depending upon the makeup of the different waters where wild rice grows. Some environmental groups oppose this because they say the state doesn’t have enough professional staff to sample and monitor all of the state’s 1,300 wild rice waters.
Last summer MPCA crews visited several wild rice areas to collect sediment samples. Multiple samples were gathered from each site and will be analyzed for organic carbon and iron.
Organic carbon provides food for bacteria and converts sulfate to harmful sulfide while iron often binds with sulfide, making it harmless to plants. MPCA uses a formula derived from this iron/ organic carbon data to determine the sulfate limit for each of Minnesota’s wild rice waters.
However, University of Minnesota Duluth biologist John Pastor disputes that iron sulfide protects plants. His research shows that iron sulfide can coat wild rice roots, which inhibit their nutrient intake, and those affected plants produce fewer and smaller seeds. He has called the MPCA formula “scientifically indefensible.”
One of the things MPCA is trying to determine is how often each site needs to be tested, and how the data from multiple samples should be combined.
Before MPCA settles on a wild rice sulfate standards rule they will hold a public comment period, which will occur sometime in October. This Request for Comments is the first of the rulemaking notifications required by the Minnesota Administrative Procedures Act. General comments will be accepted about the MPCA’s draft proposed sulfate standard and the list of wild rice waters where the standard will apply will be included.
The MPCA said this public notice would not be the last chance for the public to provide comments on this rulemaking.
MPCA’s Phil Monson will speak on the proposed wild rice excess sulfate rule at the Minnesota Water Resources Conference in St. Paul on Wednesday, October 14.
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