Back Forty Mine

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The Back Forty Mine is a planned open-pit mine in Menominee County in Michigan’s Upper Peninsula, next to the Menominee River. It would extract gold and zinc from metallic sulfide ore and process ore on site with a mill that uses flotation and cyanide. The underground sulfide deposit could also yield smaller amounts of copper, silver and lead. The project is owned by Gold Resource Corp, which acquired Aquila Resources in 2021.

The plan requires five permits: mining, air, water discharge, wetlands and dam safety. Michigan issued a draft mining permit in 2016. The river and surrounding wetlands are a major concern because the site sits close to important water and habitat. Regulators and environmental groups worry that acidic mine drainage could harm water quality and aquatic life and, through the river system, affect Lake Michigan. The Menominee River is a key waterway draining a large area of the Upper Peninsula and northern Wisconsin.

The mine would sit about 50 miles (80 km) upstream from the river’s mouth, in the Lower Menominee River area. The site is part of a watershed that has been recognized for water quality needs and previously designated as a Great Lakes Area of Concern, though it was delisted in 2020. An administrative process in 2018 allowed the air and water discharge permits, but the wetland permit was denied in January 2021 for incomplete information. After acquiring Aquila Resources, Gold Resource Corp. began redesigning the project to reduce the pit size and move it farther from the river to lessen wetland and water impacts.

The Menominee Indian Tribe opposes the mine, citing archaeological and cultural sites in the river’s watershed that are sacred to the tribe. The area includes burial mounds, raised gardens and dance rings, tied to the tribe’s history and traditions. The Menominee River Walk, a 2016 three-day, 100-mile event, also highlighted concerns about the mine’s potential effects on the river and wetlands.

Officials in Michigan, with support from regional lawmakers, have discussed the potential economic benefits of the project, including jobs in construction, mining and related administration, if the project proceeds.