Canadian pipeline company Enbridge aims to build the Northern Gateway pipeline to deliver around 525,000 barrels of so-called tar sands oil from deposits in Alberta to the port of Kitimat in British Columbia.
A 40-page report published by the University of British Columbia said spill cleanup costs and economic loss from a major tanker spill off the provincial coast could erase gains from the planned pipeline.
"There is a lot of rhetoric around the 'potential' economic gains of this proposed project, but the hard numbers are showing the risks can outweigh the gains," Rashid Sumaila, a co-author of the report, said in a statement.
A medium-impact spill, defined in the study as a 63,000-barrel spill, would equate to around $189 million in losses for the regional economy.
A section of the Enbridge Lakehead oil pipeline system ruptured in Michigan in 2010, releasing about 20,000 barrels of so-called tar sands into regional waters. That spill was the costliest onshore incident in U.S. history, though Enbridge said the severity of that release was rare.
No public comment was available from Enbridge on the UBC study, which was supported by the World Wildlife Fund Canada.