While TransCanada Corp. insists Quebec will see a $5.8-billion boost to its gross domestic product and secure a significant chunk of employment worth 50,000-person years if its Energy East pipeline is approved, some local leaders aren't so sure.

For a number of regional lawmakers and business people in communities bordering the St. Lawrence River, the project represents the possible destruction of their economic lifeblood: tourism. They simply don't believe the benefit projections from TransCanada. And they fear one small spill from the tanker ships slated to carry the crude for export will wipe out decades of effort they've spent luring visitors to their nature-rich regions.

"Water is our life. And I have serious concerns about what this project will mean for our local economy," said Hugues Tremblay, mayor of Tadoussac, a village at the mouth of the Saguenay River that's become synonymous with whale watching. "Those accidents in the Gulf of Mexico and with Japan's nuclear reactors weren't supposed to happen but they did. We're not insulated from a mishap either."

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The opposition of Mr. Tremblay and some other mayors of nearby towns reflects the challenge TransCanada will face in the months ahead as it works to secure backing for what would be the continent's largest oil pipeline, a 4,500-km span carrying crude eastward from Alberta. In Quebec the fight goes beyond the traditional not-in-my-backyard dissent, with whales having the potential to become a key symbol for opponents.

Energy East's driving rationale is to get Western Canada's landlocked crude to market and about half of the pipeline's volume would be slated for export.

Under TransCanada's project description filed to the National Energy Board, the pipeline would link to a newly planned marine export terminal and storage facility at the port of Gros-Cacouna near Rivière-du-Loup. The site is just across the river from the Saguenay-St. Lawrence Marine Park, a national marine conservation area known for its colony of beluga whales. A study cited by the company in its filing found the belugas, an endangered species, have 28 areas of so-called "high-residency" in the St. Lawrence, including one area next to the proposed Cacouna terminal site considered a key calving spot.

Oil tankers will call at Cacouna about 175 times a year under the pipeline plan, driving up existing traffic on the river by about 2 to 3 per cent, the company said. The 760-metre-long berthing facility will be able to accommodate two Suezmax ships at a time.

TransCanada is currently doing underwater testing to assess the impact of its plans on the whales and other marine life. That's separate from other work to support its permitting application for preliminary geotechnical work at the Cacouna site. Its filing proposes several mitigation measures to minimize the impact of the project construction on the animals, including using vibrating piles to reduce underwater noise.

Even as some of Quebec's most prominent business voices support the $12-billion project, other societal leaders are vowing to fight it on grounds that the risks outweigh the benefits. Premier Philippe Couillard's Liberal government has said Calgary-based TransCanada has work to do to win its approval for the plan.

"We're on our knees for what probably amounts to about 20 or so jobs," said Sylvain Tremblay, the mayor of Saint-Siméon who also represents the larger regional county municipality of Charlevoix Est.

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"We're being asked to pay the price so people somewhere in the rest of Canada might make more money."

Quebec's largest employers group takes a wider view.

"The St. Lawrence River has been the heart of Quebec's economic development going back to colonial days," said Yves-Thomas Dorval, head of the Montreal-based Conseil du Patronat, noting that ships have been using the river to carry crude for decades.

"In my opinion, a region can't ask for financial help from the government in one breath and then in the next breath, when there's economic development, say 'We don't want it.'"