STEPHENSON — Aquila Resources, the company behind a planned mineral mine in Menominee County, announced Monday it has received the fourth and final permit necessary for the mine to be constructed and begin operations.

Once completed, Back Forty Mine will be used to mine zinc, gold, copper, silver, and lead. More than $80 million has already been invested in the project with the cost of the mine’s construction estimated to cost another $260 million.

The wetlands permit announced Monday was issued by the Michigan Department of Environmental Quality following a rigorous review process. The permit also includes conditions requested by the federal Environmental Protection Agency (EPA) that strengthen protections for water quality and other natural resources.

“We commend the work of everyone involved with this process. Community members, local leaders, state and federal regulators have all left their mark on this wetlands permit. This is a very significant milestone and we believe this collective effort has resulted in a robust environmental permitting process that allows us to move forward and build a world class mining operation,” said Mike Welch, chief operating officer of Aquila Resources.

At its deepest point, the open pit mine could be 750 feet and roughly 2,200 feet long. The mine’s total surface area is expected to be about 83 acres. Also, the mine’s closest point to the Menominee River would be about 150 feet. Waste, such as rocks and tailings from mining, would be a minimum of 1,100 feet from the river.

Concerns over the location of the mine, which will be constructed near the Menominee River, prompted multiple protests and Wisconsin’s Menominee Indians to file a federal lawsuit in late January, alleging Michigan lacks the proper jurisdiction to issue a wetlands permit to the company. The tribe contended the U.S. Environmental Protection Agency improperly granted the Michigan jurisdiction over the Menominee River and adjacent wetlands in 1984 and argued the U.S. Army Corps of Engineers has the rightful jurisdiction because the river and its wetlands are interstate waters.

However, according to a release from Aquila Resources issued Monday, the Back Forty Mine will commence pre-construction activities immediately, including the completion of the feasibility study, finalization of the Project Execution Plan that allows preparation for the construction and operational readiness of the Back Forty Mine, and continued discussion with prospective financial partners to secure necessary project capital to build the mine.

The MDEQ had previously issued Aquila the Nonferrous Metallic Mineral Mining permit, the National Pollutant Discharge Elimination System (NPDES) permit, and the Air Use Permit to Install needed to begin the project.