AUGUSTA, Maine — There hasn’t been an active mining operation in Maine for 40 years, but the prospect of new mining activity in Aroostook County is fueling a State House debate over the environmental effects of open-pit mining.

During an afternoon work session Wednesday, the Legislature’s Joint Committee on Environmental and Natural Resources discussed a proposed amendment to Maine’s existing Metallic Mineral Mining Act that is targeted at protecting both groundwater and downstream surface waters from pollution associated with mining operations.

Much of the discussion Wednesday focused on how to hold mining companies accountable for water pollution and other cleanup costs after a mine closure.

Rep. Jeff McCabe, D-Skowhegan, introduced the legislation in response to Canadian-based Irving Energy’s interest in developing an open-pit metals mine on a parcel that it owns on Bald Mountain, which is located 11 miles northwest of Ashland.

While McCabe’s amendment — LD 1302 — doesn’t preclude open-pit mining, it does require regulatory and monitoring safeguards designed to preclude both on-site and downstream water pollution.

“The [amendment] will enable a well-designed mine to operate and help guard against a mine causing groundwater contamination that becomes impossible to capture and treat,” McCabe said in a recent public hearing on his proposal. “The amendment will help protect Maine taxpayers from the risk of potentially paying millions of dollars in future cleanup costs.

“If mining is going to be done in Maine, then it must be done right, particularly in terms of protecting the environment from [environmental] impacts and protecting taxpayers from being stuck with cleanup costs,” McCabe said.

The proposed regulations also would require mine operators to establish a trust fund that would cover any cleanup costs after closure. Maine’s last open-pit mine was the Callahan Mine in the Hancock County community of Brooksville, which mined zinc and copper ore between 1968 and 1972. Since 2002, the long-abandoned mine has been a federal Environmental Protection Agency “superfund” site, with cleanup costs for soils and ore remnants contaminated with lead and arsenic conservatively estimated at $32 million, with Maine taxpayers footing 10 percent of that bill.

McCabe’s proposed regulations also would require applicants for a mining permit to identify a mine elsewhere in the United States located in a climatic and geological setting similar to Maine’s that has operated for at least 10 years without polluting groundwater or surface water.

“I believe this is a common sense requirement that will protect Maine from being a guinea pig,” McCabe said.

The new regulations that McCabe is proposing are similar to those in place in Michigan and New Mexico, two states with active mining operations.

“[New regulations] will help guard against a mine that might be operated for five or 10 years, but then needs an active wastewater treatment system for hundreds or thousands of years,” McCabe said in his public hearing testimony. “Mines that require perpetual care create a major risk to taxpayers, because at some point down the road public dollars would be needed to keep the pollution treatment facilities operating.”

The proposed new regulations are opposed by the Maine State Chamber of Commerce, which views a resurgence in mining as an economic development opportunity. The organization claims an Irving Energy mine in Aroostook County would create as many as 700 direct and indirect jobs and would generate as much as $120 million in state and local taxes.

“These bills if enacted, for all intents and purposes, would end all possibility of mining in Maine,” Ben Gilman said on behalf of the state chamber. “Bring back an industry to the state that has economic promise, an industry that has the ability to create good paying jobs, grow the economy in an area where jobs are scarce and economic development is so desperately needed.”

Irving Energy did not respond Wednesday to phone calls from the BDN seeking comment on the legislation.

Lawmakers on the committee tabled LD 1302 during Wednesday’s work session.