Environmentalists are going on offense against a proposal by Enbridge Pipelines Inc. to turn shipments along one of its Canadian lines from west to east, stoking New England resistance over what they warn is a plan that ultimately would ship heavy oil-sands crude to the Maine coast.

A report released yesterday by the Natural Resources Defense Council (NRDC), the National Wildlife Federation and 17 other green groups charges Enbridge with taking a piecemeal approach to bringing emissions-intensive fuel through Vermont, New Hampshire and Maine. While environmental groups have built resistance in recent weeks to what they bill as an East Coast version of the Keystone XL pipeline, the new effort takes a more local tack by naming eight American locales -- from Lake Ontario to Maine's Sebago Lake -- that they say could be at risk from a potential spill of oil-sands crude.

"Tar sands oil companies have clearly stated their interest in accessing eastern markets" to ship Canadian oil overseas, including to the same Gulf Coast refineries that would benefit from Keystone XL, wrote the report's chief authors from NRDC.

At the crux of their case is the potential for Canada's oil industry to benefit from the reversal of not only Enbridge Line 9, the 240,000-barrel-per-day link between Montreal and the Ontario border town of Sarnia, but a separately owned pipe that connects Montreal with Portland, Maine.

Enbridge, which is still dealing with the fallout from a 2010 leak of 800,000 gallons of fuel from an oil-sands crude line running through Michigan, denies any attempt on its part to resuscitate a once-planned Canada-to-U.S. eastern line.

That project, known as Trailbreaker, "was terminated in 2009 due to lack of commercial support and is not being pursued," Enbridge spokesman Graham White said via email. "Line 9 is a completely separate project that is for Eastern (not coastal) access to Canadian refineries only and does not involve lines going through the U.S."

Given the outside ownership of the Portland Montreal Pipeline, White added, "it is therefore not appropriate or representative for us to comment" on its future. Representatives for that Montreal-to-Portland link, partly owned by Canadian oil-sands companies Imperial Oil Ltd. and Suncor Energy Inc., have said they currently do not plan to seek a reversal of crude flow.

Green advocates note, however, that the pipeline's owners lost a court battle in February over adding a new pumping station that would ultimately be needed to begin carrying oil to the Maine coast. Sending oil-sands crude out of Portland also would require expanding the town's marine terminal to accommodate large tankers, the report's NRDC authors wrote, raising the risk of "a significant spill [that] could crush Maine's economically and culturally vital commercial fisheries."

Even as Enbridge seeks to extricate its Line 9 plans from any decision made by the Portland Montreal line's owners, the activists behind yesterday's report are pressing Canadian regulators to consider the two projects as possibly connected while weighing the company's application for a reversal.

Enbridge also is seeking a green light from Canada's National Energy Board for its Northern Gateway line connecting the Albertan oil sands region with ports in British Columbia. Often cited by congressional Republicans and oil companies as a potential oil sands route to China, Northern Gateway faces steeper political opposition than the smaller Line 9 project, including criticism from First Nations aboriginal peoples who have strong legal authority over energy development that crosses their land.

Click here to read the green groups' report.