The Minnesota Court of Appeals reversed the renewal of the wastewater discharge permit for U.S. Steel Corp.'s Minntac iron ore mine made by the state's Pollution Control Agency, the Associated Press reported.

The agency first issued the permit in 1987 and renewed it in 2018 despite a dispute over whether the mine has to comply with a state law intended to protect wild rice beds by limiting sulfate discharge, according to the newswire's report. The court sent the dispute back to the agency for further proceedings.

A 13.6-square-mile tailings basin, which holds mine waste and wastewater that is later reused for additional ore processing, is contained within the Minntac ore processing facility. Sulfate levels build up in the basin, and the contained water seeps into local ground and surface waters.

The ruling came in a consolidated set of appeals by U.S. Steel, environmental group WaterLegacy and the Fond du Lac Band of Lake Superior Chippewa.

The Pittsburgh-headquartered steelmaker challenged the Pollution Control Agency's denial of its request for a variance from groundwater quality standards. WaterLegacy and the indigenous group contested that the agency misinterpreted the federal Clean Water Act and formulated permit conditions that insufficiently protected surface waters.

The Minnesota Center for Environmental Advocacy said the ruling not only failed to back the Pollution Control Agency's decision that specific limits to avoid downstream pollution were not necessary but also gave mining companies the upper hand by preventing the state from enforcing groundwater standards.

The legal counsel representing WaterLegacy pointed out that all sides have 30 days to ask the state's Supreme Court to hear the case.