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Soudan State Park contains Minnesota's first iron mine and offers tours through parts of the old underground mine workings. The mine began in 1884 as an open pit before switching to an underground operation in 1892. U.S. Steel operated the mine from the 1920's until it closed in 1962. The average mine dewatering discharge is around 60 gallons per minute and contains copper and cobalt in excess of the permit standards of 0.020 mg/L copper and 0.005 mg/L cobalt. Annual average concentrations have varied from 0.083 to 0.5 mg/L copper and 0.006 to 0.026 mg/L cobalt. Despite at least 60 years of discharge, all the copper and cobalt are removed in about a 5-acre portion of a downstream wetland. Copper concentrations in the peat ranged from around 100 to 3380 mg/kg, and cobalt from 20 to 260 mg/kg. Both metals are strongly bound to the peat; less than 0.5% was removed in laboratory extraction tests About 94% of the total copper and 44% of the total cobalt come from one area in the mine. In 1998, DNR proposed to treat this water in an organic substrate/ limestone bed. Remaining low levels of metals in the mine discharge would be removed within the 5 acres of the wetland that already had elevated concentrations. To compensate for the use of the wetland, an equivalent area of wetlands would be restored in a state park in the southern part of the state. This proposal was approved in 1999 and the wetland mitigation was completed. Despite having approval, land ownership issues and some internal reluctance about using a natural wetland stalled construction. In 2002, the Department signed a compliance agreement and installed an ion exchange unit to remove the majority of metals from the largest source. As soon as the unit was installed, a white precipitate appeared in the inflow water and plugged the unit. In 2006, the Department was fined and signed a stipulation agreement. The current proposal is to construct a wetland at the park to treat the entire mine flow. The estimated cost for this proposal is about 4-5 times the original treatment plan developed in 1998.