PORTLAND, Maine — State environmental groups decried a decision by the Canadian government late Thursday afternoon to allow the reversal and expansion of a pipeline leading to east Montreal, where they say controversial tar sands oil can now be pumped almost to the New England border.

The Natural Resources Council of Maine, Sierra Club, 350 Maine and Environment Maine have long considered the change of direction of the 397-mile section of Enbridge Line 9 — from North Westover, Ontario, to Montreal — the final link before the Portland Pipe Line Corp. seeks to reverse its pipe through Maine and complete energy giant Enbridge’s path from the oil sands of Alberta to tankers in the Atlantic port of South Portland.

Currently, Line 9 and the connected 236-mile-long Portland-Montreal line pump from east to west, carrying the less controversial crude oil inland from the tankers.

“Today’s decision brings toxic tar sands oil right to New England’s doorstep, and one step away from flowing south through Vermont, New Hampshire and Maine,” said Dylan Voorhees, clean energy director for the Natural Resources Council of Maine, in a statement. “This decision should put Maine on high alert for the threat of tar sands transportation through our state. That would be unacceptable. Now is the time for the U.S. State Department to commit to an environmental review of any tar sands project in our state.”

Soon after the Canadian government’s announcement, Maine Sen. Angus King called for a presidential permit requirement and environmental impact study of any proposal to let the oil flow through Maine.

“My constituents have consistently expressed concern at the lack of any environmental review of a project of this nature, given that there appears to be no substantive state review process that would be triggered,” King said in a release. “Yet, this pipeline runs through very important — and ecologically fragile — parts of Maine, including Sebago Lake, the drinking water supply for the greater Portland area.”

U.S. Rep. Chellie Pingree said the decision shows the need for regulatory oversight of the pipeline that runs across Maine.

“This just shows why a new presidential permit should be required for reversing the flow of any pipeline that comes into the United States. 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 release.

“The decision by the Energy Board brings tar sands oil into our backyard and really raises the stakes for Maine,” Pingree said. “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.”

Representatives of the Portland Pipe Line Corp. have long argued the company has no plans to reverse its flow and that Enbridge’s eastward path could extend from Montreal to coastal Canadian ports instead of South Portland.

As with the political lightning rod Keystone XL pipeline proposed to transport the heavier bituminous oil from Canada through midwestern U.S. states to the Gulf of Mexico, environmentalists have protested the establishment of a tar sands pathway to international markets across Canada’s eastern provinces and northern New England.

Several Maine towns have passed resolutions declaring opposition to the transportation of oil sands bitumen across their borders, including Casco, where the pipeline passes near Sebago Lake, the source of drinking water for 15 percent of all Mainers.

Environmentalists have proclaimed the toxic, corrosive oil being harvested from the sands of Alberta to be three times more likely to wear down aging pipelines and leak than the more traditional crude. And places where those leaks have taken place, such as near the Kalamazoo River in Michigan in 2010, have contaminated the water there for years afterward.

“Tar sands pose the most significant threat to Sebago Lake that I’ve seen in my 34 years of fishing on the lake,” said Eliot Stanley, a board member of the Sebago Lake Anglers Association, in a statement. “The fact is that a tar sands pipeline spill into the Sebago-Crooked River watershed would devastate the lake, its fisheries and southern Maine’s clean drinking water supply. We cannot permit another Kalamazoo River catastrophe. This irresponsible action by the Canadian Energy Board poses a threat to all Maine citizens and public officials.”

In November, South Portland voters at the polls narrowly defeated an ordinance that would have prevented upgrades to the town’s Portland-Montreal Pipe Line terminal necessary to accommodate the oil sands bitumen.

Opponents of the measure argued the ordinance was too broadly written and would have also blocked important upgrades at other waterfront businesses as well, effectively choking off all waterfront advancement for the sake of a more isolated goal.

City leaders have since approved a moratorium to buy time to consider a more specific ordinance language that could block the movement of the heavier oil through their port — and thus, potentially cut off the tar sands oil export path through Maine — without also hindering other waterfront businesses.

The oil lobbyist American Petroleum Institute has hinted it would file a lawsuit against the city if it continued to obstruct the pipeline’s operations, arguing the export of oil is the protected purview of the federal government, not a local municipality.

On Thursday afternoon, the Canadian National Energy Board approved an Enbridge plan to reverse the flow of its North Westover-to-Montreal line, as well as increase the capacity of the line from 240,000 barrels per day to 300,000 barrels per day starting as far back in the line as Sarnia, Ontario — another 120 miles west of North Westover.

The board’s decision, which came after 15 months of hearings and deliberation, also grants Enbridge the allowance to transport heavy crude oil through the sections of pipeline in question.

Seth has nearly a decade of professional journalism experience and writes about the greater Portland region.