SOUTH PORTLAND — Diluted bitumen or “tar sands” oil is on track to come a bit closer to the city – about 400 miles closer, to be exact – igniting concern from some residents and calls for more oversight from independent Maine U.S. Sen. Angus King, and U.S. Rep. Chellie Pingree, D-Maine.

Last week, the National Energy Board of Canada approved plans to fully reverse the a pipeline to send tar sands oil from Alberta to Montreal. The pipeline in Montreal connects to South Portland, where for more than 70 years Portland Pipe Line Corp. has pumped oil westward.

Opponents worry there could be plans to reverse the pipeline and bring tar sands oil from Montreal to South Portland. They believe doing so could have environmental consequences, if the pipeline breaks, and would threaten the city’s air quality at the pipeline’s waterfront terminus.

“The decision by the Energy Board brings tar sands oil into our backyard and really raises the stakes for Maine,” Pingree said in a prepared statement. “Communities across the state have said they don’t want tar sands crude flowing through environmentally sensitive areas like Sebago Lake. The decision today makes it even more likely that we could soon be facing that possibility.”

Portland Pipe Line, a subsidiary of Montreal Pipeline Ltd., has said it does not have plans to reverse the flow of its 236-mile pipeline. However, it did explore the potential of such a project in 2008, before the economic recession made the project untenable. And Chief Executive Officer Larry Wilson has frequently said the company would pursue a potential project in the future if it makes economic sense.

In response to the Canadian announcement, company spokesman Jim Merrill issued a statement that “Portland Pipe Line Corp.’s previously stated position that there is no project to reverse the flow of its pipeline proposed, pending or imminent is unaffected by announcements regarding other Canadian pipelines.”

Pingree, however, urged the Obama administration to require Portland Pipe Line to apply for a new permit if it decides to bring tar sands to South Portland. The company already has a permit to operate across the international border.

“If Maine people are to have a say in whether tar sands oil is pumped through our state, the Administration is going to have to require a new Presidential Permit and environmental review,” Pingree said in a statement.

King, meanwhile, urged the State Department require Portland Pipe Line to acquire a new Presidential Permit if there is a move to import tar sands, and added that the company ought to be required to “prepare a comprehensive Environmental Impact Statement.

“The people of northern New England deserve a full assessment of that risk and the likelihood of a spill if the pipeline is reversed to convey tar sands to South Portland,” King wrote to Secretary of State John Kerry.

Since last fall, South Portland has had a moratorium on any development proposals related to tar sands, and for the past few weeks a draft ordinance committee has been researching and developing a proposed ordinance with the goal to prohibit tar sands from coming to the city.

Crystal Goodrich, a leader of the anti-tar sands group Protect South Portland, expressed continued determination after hearing the Canadian decision.

“We have the opportunity to stop it, so we’re just more and more determined,” she said. “We’re going to continue to work with the city, providing insight for the (committee). We really feel like the major impact we can have is to ensure the public is educated and provide support for the (committee) to get an ordinance written that will prevent tar sands from coming here. It’s the right thing to do.”

Shelby Carignan can be reached at 781-3661 ext. 106 or scarignan@theforecaster.net. Follow her on Twitter: @shelbycarignan.