The experts recommended examining data from recent Minnesota field studies that use more sophisticated models.
Some in northeastern Minnesota want the state to move faster to reduce mercury pollution in the St. Louis River.
A team of international experts found plenty to like, and plenty to criticize, in their examination of MPCA’s research.
The research was designed to determine whether Minnesota’s current sulfate standard for wild rice waters is right.
Through a series of legal victories, including one just weeks ago, tribes are extending the meaning of rights they reserved in 19th-century treaties.
The agency concluded that the range at which sulfide limits the plants’ ability to grow corresponds to a range of sulfate in the surface water of 4 to 16 milligrams per liter – neatly bracketing the current standard.
“We found there really is no threshold at which sulfide becomes toxic,” said researcher John Pastor. “As soon as you add any, you get a decline in growth rate.”