In northern Wisconsin, crews are working around the clock to drill deep into the bedrock. It’s called exploratory drilling, and the goal is to determine if a deposit of copper, gold and other minerals in the rock is rich enough to bring metallic sulfide mining back to the state.

“What we have going on here is the drilling process has just started,” Steve Donohue said.

It’s a Sunday morning in the Chequamegon-Nicolet National Forest in Taylor County.

A drill team out of Minnesota is making the final site preparations, digging a sump pit that will hold the cuttings from the drilling that is about to begin.

Donohue is on the board of directors for GreenLight Metals, the company behind the exploratory drilling.

“The drill crew is getting ready to start coring the bedrock, OK,” he said, pointing to its equipment. “That’s a hollow barrel with a diamond-impregnated tip on it, and it just cuts out a cylinder of the rock going down.”

The drill team will cut 10 feet of bedrock, use a tip called a water swivel to pull up the core, and repeat.

“This particular hole will go down about 1,500 feet,” Donohue said.

GreenLight’s field geologists will then box up the cores and bring them back to their facility.

“They log the geology, process the core, cut it up into segments, send it off to a lab,” he explained, “where the lab tests it for things like copper and gold and tellurium.”

Greenlight conducted exploratory drilling at the site in the summer of 2025.

“What we’re seeing is about 2% to 3% copper in the ore, or what we would call ore. If you look at the average deposit that’s being mined in the world, it’s maybe half a percent,” Donohue said.

The site is known as the Bend Deposit, and it was first identified and explored in the 1980s.

“Each of these is a drill hole,” said Eric Quigley, GreenLight Metals’ director of exploration, pointing to a computer monitor.

A computer model shows every exploratory hole drilled at the site in the last 40 years.

“That red represents the copper, you know, primarily the copper and gold mineralization that we’ve identified,” he said.

The current exploratory drilling is trying to expand the picture to see if the deposit runs deeper than previously known. The cores from the summer of 2025 were promising. GreenLight used a red marker to circle flecks of gold in the bedrock.

“Visible gold — within, I think, about roughly two meters, probably averaging about a third of an ounce per ton, which is extremely high-grade material,” Quigley explained.

GreenLight has conservative projections of what’s in the Bend Deposit.

“Million tons of ore, copper grade ore that was about 1% to 2% copper with good grades of gold, and now we’re finding tellurium in there,” Donohue said. “What we’re hoping to do is to expand the tonnage of that by drilling other areas around this deposit.”

The results were enough for GreenLight Metals to secure another $11 million in funding from investors to continue the exploratory drilling. But that doesn’t mean a mine is coming to Taylor County in the immediate future.

“We’re years away from ever being at the point where we would actually start the permitting process with the DNR and the federal government on an actual mine out there,” Donohue said at a town of Westboro meeting on Feb. 9.

Previous mining proposals in Wisconsin have received hostile reactions, so GreenLight Metals is being proactive in community outreach, presenting updates to groups like the Westboro town board.

“We want to be coming in and talking to you and other local units of government,” Donohue said in one such update.

“The public, I would say, is about 70% enthusiastic about the potential,” he explained in an interview. “And then there’s another group of people who obviously have concerns about what it means for the environment.”

A question asked during the town board meeting offered one example.

“I know you guys take water from the Yellow River to the drilling. What is there in the permit that maintains a minimum flow in the Yellow River,” asked Susanne Adams, an attendee at the meeting.

The concerns are primarily focused on environmental impact. The Bend Deposit is under national forest land, and just a few hundred yards from the Yellow River.

“We just keep each other informed — informed about the issues protecting the environment,” Scott Stalheim said.

He and Cathy Mauer are part of a group called Friends of the Yellow River.

“Well, I think there should not be mining in this area for a lot of those reasons,” said Stalheim. “That’s my personal opinion, and I think many of the Friends of Yellow River would feel that way.”

The group is small and private, mainly focused on educating members. An open question is whether they should become more public and vocal.

“We had quite a few people with different opinions,” Mauer said.

“Some people say that because it’s just exploratory mining that, well, it doesn’t matter much,” Stahlheim added. “And until a real mine comes, then we’ll start to worry about it.”

One group that is publicly opposing the drilling is the Wisconsin chapter of the Sierra Club.

“I think it’s a fundamentally incompatible land use to have on our national forest,” said Dave Blouin, the state mining committee chair for the chapter. “The environment here is especially water-rich, and that makes it really almost incompatible with modern mining, especially metallic sulfide mining.”

The issue is the copper and gold are found within bedrock heavy with sulfides, as can be seen in the cores from the Bend Deposit.

“There’s a very stark contrast between the unmineralized rock and the heavy sulfide content within the massive to semi-massive sulfide section,” Quigley explained while pointing to one such core.

After the ore is mined, it has to be processed. Sulfides in the rock produce acid when exposed to air and water.

“Imagine a finely ground up, almost powdery waste material that’s left over from the processing to skim off the metals in the first place,” Blouin described. “And you have this acid-producing material that is chock-full of nasty toxics that — if they get into groundwater or surface waters or wetlands — are absolutely polluting and damaging the environment. So this includes lead, mercury, arsenic.”

Most of the environmental damage from metallic sulfide mining comes from leaks at the tailings facilities polluting the groundwater.

‘That’s an area that has gone through tremendous changes, in terms of how the tailings facilities are managed,” Donohue said.

A video from another mining company shows the processing plant and tailings facility for the Eagle Mine, a metallic sulfide copper mine in the Upper Peninsula of Michigan.

Donohue said GreenLight doesn’t have designs yet, but a processing facility in Wisconsin would have an engineered liner and a drainage system —- and would be capped at the end of its lifespan.

‘It’s very analogous to what you would see for a municipal waste landfill,” Donohue said.

He also said the ore wouldn’t be processed in the national forest.

Bend is one of four deposits across northern Wisconsin that GreenLight would hope to mine, and the processing and tailings facility would be at one centralized location.

“That allows us to then capitalize — create economies of scale where we can have a pipeline of projects that over a generation or multiple generations are feeding into that operation,” Donohue said.

Blouin said GreenLight is the fourth company to explore Bend, and each previous effort has shown it wasn’t economically viable.

“The overall deposit at Bend is under 2% copper, meaning 98% of the material that comes out is waste,” he said.

Donohue said a lot has changed since the last exploration at Bend. For one, the demand for copper is up, which is raising the price for copper.

“There’s a lot more demand in the system because of things like AI, electric vehicles, building out the electric grid — it’s going to take a lot of copper,” Donohue said.

GreenLight has also discovered a rare earth element called tellurium, which is labeled by the U.S. as critical to the creation of solar panels.

“In the drill program that was completed this past summer, the assay data indicated about 340-350 grams of tellurium per ton in the material,” Donohue noted.

The old argument for mining in Wisconsin focused on the miner on the state flag — or the need for jobs — but the new argument is national security.

“We’re very reliant on foreign sources for many critical metals,” Donohue said at the Westboro town meeting. “If we don’t want to be dependent on adversaries for these critical metals, we’re going to have to do it here domestically.”

Blouin isn’t buying the national security argument, simply because Bend isn’t big enough to factor in.

“In terms of the amount of metals that the Bend Deposit can produce, it’s not going to dent or make any real difference in terms of national security for the United States,” he said.

Blouin understands any mining permit is years away, but even the exploratory drilling comes with concerns.

“It’s concerning to us because that potential — and they’ve described it as a potential mining district across northern Wisconsin — is deeply concerning. Every potential proposal results in risk to the environment, to air, to water, to habitat, in multiple locations and forever,” he said.

Donohue reiterated there is a lot more drilling and a lot of studies to go, but at some point in the future, the economics will make the Bend Deposit viable.

“If you look at these types of belts across the world, this is one of the larger, undeveloped belts of its type in the world,” he said. “So from that perspective, I think — very confident that there will be mining again in Wisconsin.”