Enbridge defends Northern Gateway pipeline 19 (UPI) -- The proposed Northern Gateway oil pipeline is a delivery issue, not a production one, and won't lead to significant increases in emissions, said Enbridge. Robert Mansell, an economist working for Enbridge, told a review panel in Canada the project was meant to tap into new markets not necessarily increase production of crude oil. "Enbridge's proposal is not changing the western crude supply," he was quoted by the Edmonton Journal as saying. Northern Gateway would carry around 585,000 barrels of so-called tar sands oil a day from Alberta. Provincial and aboriginal leaders in British Columbia have expressed concerns about the potential environmental impacts of the project. A pipeline operated by Enbridge in Michigan ruptured in 2010, leading to the costliest onshore spill in U.S. history. Enbridge during the hearing faced challenges from critics who said the pipeline would cause an increase in greenhouse gas emissions because of refinery developments associated with the project.