A Ramsey County judge will hear arguments Thursday in a lawsuit brought by the Minnesota Chamber of Commerce against the state's implementation of its sulfate standard for wild rice.
The state's limit on sulfates in wild rice waters has been controversial since the Minnesota Pollution Control Agency imposed it on taconite mines a few years ago.
Sulfates come from mines, wastewater treatment plants, and other industrial facilities.
The Chamber of Commerce said the MPCA is exceeding its authority in applying the limit to waters where wild rice grows naturally, rather than just in cultivated wild rice beds. The group also says the rule is unconstitutionally vague.
The MPCA is studying to determine whether the limit, set in 1973, is scientifically valid.
Results probably won't be known for at least two years, leaving taconite companies to try and comply with a rule which could change.