AUGUSTA — A hotly debated bill that would rewrite Maine’s metal mining regulations was dealt a decisive setback Thursday in the House of Representatives after a lengthy and contentious debate.

The 109-36 vote to reject the complex proposal was preceded by more than two hours of floor speeches. Opponents spoke with conviction that the rules wouldn’t do enough to protect against pollution in lakes and rivers, while leaving taxpayers with the cleanup costs. Proponents countered that existing laws have shut down an industry that could employ thousands of workers, including hundreds at an Aroostook County mountain.

The proposal had received an 8-5 endorsement from the Environment and Natural Resources Committee on May 14 after lawmakers spent about 60 hours in public hearings and work sessions amid heavy lobbying by supporters and opponents. Aroostook Resources, a subsidiary of J.D. Irving, has spent nearly $70,000 lobbying this session for a regulatory change that could lead to the mining of Bald Mountain, which is rich in precious metals. Irving has been countered by lobbying from influential environmental groups, including the Natural Resources Council of Maine and the Maine League of Conservation Voters.

The pressure from outside interests fueled Thursday’s feisty floor debate. Legislators who supported the bill argued that the rewritten rules were necessary to allow mining activity that is already legal but logistically impossible because of conflicting regulations.

Rep. Robert Duchesne, D-Hudson, said existing regulations make it “OK to mine just as long as you don’t dig.”

Duchesne, a member of the environment committee who has been involved in the issue for years, said mining should be heavily regulated, but that the current rules effectively outlaw it. He said a 2013 effort to update the regulations to conform with a 2012 law was subverted by environmental groups.

Rep. Ralph Tucker, D-Brunswick, also a member of the environmental panel, argued that the rules in the bill, L.D. 750, were insufficient and that lawmakers had been overly dependent on interest groups and lobbyists instead of neutral experts. Specifically, Tucker said the rules provide few protections in the event a mining operation pollutes the groundwater or a nearby water body. He said the $500,000 permit fee and the $20,000 to $50,000 annual fee to operate a mine would not cover an expensive disaster.

“The committee should have made the DEP (Department of Environmental Protection) prove that the proposed rules were adequate,” Tucker said. “Instead, it decided to make the public and the environmental community prove that the rules weren’t adequate.”

AROOSTOOK COUNTY NEEDS THE JOBS

The House vote is a stinging defeat for the bill’s proponents and sets up the possibility that the bill will fail or be carried over until next year. Sen. Tom Saviello, R-Wilton, co-chairman of the environmental committee, played a key role in drafting the legislation. The Republican-controlled Senate could approve the bill, but it appears unlikely that the two chambers could resolve significant differences with the legislative session scheduled to end June 17.

Rep. John Martin, D-Eagle Lake, expressed frustration during the floor debate. He framed the proposal as an opportunity for Aroostook County, saying southern Maine has had to fund Aroostook’s schools and has become a destination for its youth.

“Aroostook County can’t take care of its own” and needs to rely on its natural resources, Martin said.

He said the bill and mining at Bald Mountain present an opportunity for a 30-year job for residents of the region. Martin also said he does not have a conflict of interest regarding the legislation – a reference to questions that have been raised in the media about a $250,000 debt that his business owed to Irving Oil, another company owned by the wealthy Canadian family. Irving Oil forgave roughly $150,000 of the debt as part of a bankruptcy case last year.

Rep. Gay Grant, D-Gardiner, countered that the proposal was “written by the mining industry for the mining industry.”

The bill includes some site restrictions on mines, as well as monitoring, closure and cleanup requirements for mining companies. The proposal also would require mining companies to provide “financial assurance” to cover potential environmental problems and mandates treatment of contamination for at least 20 years after a mine closes.

YEARS OF BATTLING OVER NEW RULES

Lawmakers began reviewing Maine’s now-24-year-old mining rules in 2012 at the behest of J.D. Irving and Aroostook County lawmakers.

The state’s largest landowner, J.D. Irving owns the land and mineral rights on Bald Mountain, a remote spot 35 miles west of Presque Isle that contains deposits of gold and silver, among other minerals.

Although Bald Mountain has dominated discussion of the mining rules, the Maine Geological Survey lists 10 sites of “significant known metallic mineral deposits” in the state.

The DEP proposed a set of rules last year, but the Democrat-controlled Legislature rejected the rules and Republican Gov. Paul Le-Page vetoed a bill directing the department to revise the rules. The most recent rules are intended to end the legislative standoff.