The effects of a Jan. 20 decision by Harpswell voters whether to approve a lease agreement negotiated by town leaders with Conoco Phillips and Transcanada for a $350 million liquefied natural gas terminal will extend far beyond the 70 acres that the plant would occupy at the former Navy fuel depot on Route 123.

If approved, the project could bring significant environmental changes to Casco Bay, both during construction and over the life of the facility. While there is certainly intense debate within this Casco Bay town of 4,688 registered voters, the far-reaching consequences of the project could be decided by a margin of a few hundred ballots.

The fact that many questions cannot be answered about the so-called Fairwinds project until the town votes on the lease only fuels the debate. Fairwinds would be sited on part of the 118-acre former Navy fuel depot site acquired by the town in 2001. It would employ 900 workers during construction and 50 full-time during operation, a point offered repeatedly by the pro-Fairwinds faction, Friends of Harpswell.

Perhaps most enticing to them, and to residents whose property taxes rose dramatically after last year’s revaluation, Fairwinds would pay the town up to $8 million per year in lease payments, obliterating budgetary woes for decades.

For now, however, the lease question is the first and only question the companies are focusing on. Until that is decided, there are few specifics and many what-ifs. To be sure, if Harpswell gives Fairwinds the go-ahead there will be lengthy permitting questions at the state and federal level, which could easily take two years to resolve. But Harpswell locals, searching for specifics on potential environmental and socioeconomic realities ten and fifteen years down the road, find themselves forced to conjecture.

Take impacts on the lobstering, for example. Richard Thompson, an attorney hired to represent local fishermen, says that at a hearing in November they heard that the ships that would be transporting the liquefied natural gas (LNG) into the facility are not yet built. They would be 1,000 feet long, with keel clearances above bottom of only about three feet. Thompson cites the size of ships going through prime lobster fishing areas as a concern.

“It would have a huge impact on lobstermen’s ability to fish their traditional areas,” says Thompson. “Such a huge ship could be churning up the bottom with its prop-wash. Other portions of the impact include the fact that whenever one of these ships comes in and out, or even while the ship is in port, there’s a security zone that would prohibit the fishermen from fishing in the vicinity. That could get more dramatic if there’s an elevated terrorist threat. The Coast Guard would have the authority to shut down the whole bay. You’re talking about loss of the ability to fish and make a living.”

For the Coast Guard’s part it is not worth the trouble to analyze Fairwinds until a concrete proposal is on the table since the variables are too numerous. But Harpswell voters won’t have the luxury to “wait and see” the details of a formal application. If the project gets the go-ahead, local concerns will be thrown in with the testimony of corporate and government experts in the grinding Federal Energy Regulatory Commission review process. Fairwinds opponents such as the group Fair Play for Harpswell claim that the opportunity to raise concerns is now, before that process is taken out of their hands for good.

Security and navigation are key concerns expressed at Harpswell’s weekly public hearings. The LNG terminal in Everett, MA in the port of Boston provides some indication of what to expect in Casco Bay, according to Charles Colgan, professor of public policy at USM’s Muskie School. “There are safety issues, and that’s always a matter of good design and continuously excellent execution,” says Colgan. “The experience in Everett shows it can be done, even in a more challenging navigation situation. The Coast Guard will do what it has done there, and put a patrol boat on every ship movement.”

Colgan also says that the concerns voiced by local volunteer fire chief Nelson Barter about his ability to respond to an emergency at Fairwinds are “dead right.”

“The first thing Harpswell should be looking for is a substantial commitment in emergency facilities upgrades and emergency planning for the town,” says Colgan.

Environmental concerns raised by the project will have to wait for Harpswell’s vote and (if approved) the formal permitting process to be answered. The nonprofit group Friends of Casco Bay is confined to a holding pattern pending January’s vote. “We can’t say we oppose it, because we don’t know where it’ll go,” says Baykeeper Joe Payne. Just in case, his organization has posted five pages of “initial” concerns dealing with water, air, and habitat quality concerns on its website .

High among these are problems associated with constructing and operating a pipeline connecting the Fairwinds LNG plant to existing natural gas lines. The pipeline’s location won’t be determined until the permitting process is fully underway, and though an existing pipeline connects the former Navy fuel depot to Brunswick Naval Air Station, alternatives under discussion include laying new pipeline in bottom sediments across Casco Bay. Constructing a new underwater pipeline alone raises myriad questions of underwater currents, mud versus hard substrate, and marine habitat characteristics, says Payne, and once a pipeline is in place, long-term safety raises other questions.

Fresh water supply is another environmental question mark. Harpswell informed Fairwinds that its groundwater aquifer, already afflicted by saltwater intrusion, cannot handle the daily demands of 50 full-time Fairwinds employees (much less 900 construction workers at the site). The company’s proposal for intake and discharge pipes for an on-site desalination plant is raises concerns, says Payne. “To get the 5,000 gallons per day they’d need for human use alone, they will need to take in 20,000 gallons of saltwater” into the desalination plant, says Payne. “There are ways to minimize the impacts, such as getting water delivered by ship. We are opposed to a desalination plant.”

The decaying 400-foot dock at the site, comprised of 200 feet of jetty and 200 feet of dock, would have to be much larger to accommodate the giant tankers delivering LNG to Harpswell. Fairwinds proposes an 800-foot dock, and Friends of Casco Bay worries that it would include about 400 feet of jetty covering the bottom, destroying marine habitat, and disrupting currents and water quality.

Not all of Fairwinds’ environmental impacts would be negative. Compared to oil-fired generators, natural gas is relatively clean. New England suffers from chronic air quality limitations and too many days over standard. Pollution from the Midwest makes things worse. “So natural gas is critical from Maine to Virginia,” says Colgan. “Some natural gas brought into Harpswell will be sold in Maine, and the rest will go all over New England. The gas coming into Harpswell will help clean up the air upwind of us.”

Colgan, who characterizes natural gas as “the most under appreciated story in the Maine economy over the past decade,” says one only needs to look at the closure of the Maine Yankee nuclear plant to realize its importance. “We took 800 megawatts offline with Maine Yankee and didn’t even notice it. That was because of natural gas,” says Colgan. From an economic standpoint, Fairwinds would serve to stabilize the price of natural gas already being piped into the region through the Maritimes Northeast pipeline from Nova Scotia, and the Algonquin pipeline coming into western Maine via Ontario and Quebec. Colgan says that downtowns close to the existing distribution system would likely benefit, including Yarmouth, Freeport, Brunswick, and possibly Bath (if Bath Iron Works looks favorably on gas heat for its shipyard).

Beyond economic and environmental questions are the social implications of siting what Colgan describes as “a huge, region-scale project” in Harpswell. He likens its financial impact to Maine Yankee in Wiscasset. Having $8 million per year in lease payments may be too big a temptation to pass up. While Harpswell debates, Casco Bay, greater Portland, and the rest of New England are standing by.