ST. PAUL, Minn. (AP) — U.S. Steel has gone to court in a dispute with the Minnesota Pollution Control Agency over pollution limits for its Minntac iron mining operations.

Minntac has been operating under a water quality permit that technically expired in 1992. Pittsburgh-based U.S. Steel said in a statement Tuesday that if several of its long-standing requests for changes remain unresolved, the company could be forced to make significant, unnecessary investments that could put Minntac at a competitive disadvantage.

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The MPCA has delayed renewing Minntac’s permit while it updates standards meant to protect wild rice. It expects to finish that next year.

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The MPCA released a draft permit with stricter controls in November and committed itself to completing the new permit within nine months. The MPCA says the new litigation will delay any resolution.

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