GOGEBIC COUNTY, MI -- Michigan environmental regulators have cited a Canadian mining company with state law violations after exploratory drilling in the Porcupine Mountain Wilderness State Park got bogged down in rivers of mud.

Steve Casey, district supervisor for the Michigan Department of Environmental Quality (DEQ) Water Resources Division, said Highland Copper Co. of Quebec caused soil erosion and damaged wetlands on Gogebic County Road Commission property along County Road 519, which runs through the western end of the park.

The DEQ issued a formal violations notice on April 20, but Casey said the investigation into the incident is ongoing after a recent ice and snow storm felled trees and closed trails in parts of the park last week.

Locals activists say mud from the site is moving again after the wet weather despite efforts to control the erosion caused last month.

"We will not be making a decision regarding fines until all of Highland's drill sites have been assessed," Casey said. "A number of those sites are not accessible now due to wet spring conditions making woods roads impassable.

The Upper Peninsula Environmental Coalition (UPEC), a local mining watchdog group, shot photos April 2 and 4 of heavy drilling equipment navigating through deep mud along a snowmobile trail that parallels the county road.

Highland Copper contracted Idea Drilling of Minnesota this winter to punch 21 exploratory holes in the area, 12 of them on parkland, to see if a mineral deposit first discovered in the 1950s might be feasibly mined.

The April 20 letter sent to Highland Copper Vice President Carlos Bertoni referenced "uncontrolled erosion and sedimentation" that discharged into a Gypsy Creek tributary and missing required permits to move dirt and construct access through wetlands.

"A permit would not have been approved for this project in the manner in which it was undertaken," the letter read. "No efforts were taken in some instance to avoid and/or minimize impacts to the wetlands."

The letter said Highland Copper was in violation of Parts 31, 91 and 303 of the Michigan Natural Resources & Environmental Protection Act (NREPA).

The DEQ says the company must stabilize the site, restore disturbed wetlands, obtain additional permits for discharging stormwater and sedimentation, and investigate other drill sites to determine if more wetlands have been disturbed.

"Due to the severity of the non-compliance, the matter is being evaluated for escalated enforcement," the letter read, meaning DEQ is considering civil fines.

Casey said he's not sure whether the enforcement amounts to throwing the book at Highland, but he "we certainly were careful to cite all the violations we saw."

"Since that's everything in the book, maybe that is throwing the book at them."

Highland needs DEQ permission to resume exploratory drilling. The company also needs to plug holes that are still open after drilling was suspeneded last month.

"Once conditions dry up, I don't see any reason why they can't go in there as long as they avoid wetlands while doing it," he said.

"There's logging occurring all over the U.P. all summer with equipment driving on woody roads and not causing significant problems."

During spring snow melt, when "it's all gushy, is just not a good time to be in the woods and they illustrated that very well," Casey said.

Dave Anderson, a company executive in Highland's office in White Pine, said the company intends to "fully comply" with the DEQ requirements.

"Short term erosion control measures have been established," he said. "We continue to work with DEQ to address any and all concerns."

Highland had agreed to only drill on frozen ground on state-owned land, but that agreement was with the Michigan Department of Natural Resources, which does not own the underground mineral rights in that part of the park.

Highland entered into a separate agreement with Gogebic County to drill in the right-of-way along County Road 519. The road commission did not include a provision mandating that drilling only happen on frozen ground.

Despite the state law violations, Idea Drilling is an "outstanding company and we'd be lucky have them back," said Anderson. "The error was made with our team not recognize the spring break-up conditions. Spring happened rather quickly this year and certainly caught the team off guard."

The drilling is part of a new copper district that Highland is attempting to develop in Gogebic, Ontonagon and Keweenaw counties.

If enough mineable copper ore is found under the park, Highland would potentially access the ore from adjacent land outside the park through underground tunnels. It would need DEQ permits to develop the mine.

Anderson said the "full project" mine would create "hundreds" of jobs. According to the Iron Mountain Daily News, Highland executives say the mine could employ 320 people. Construction could begin next year, with the start of mining by 2021.