While opponents of the project predict disaster, Al Maki, who was the chief scientist for Exxon at the time of the 1989 Exxon Valdez spill off Alaska, said those effects would not be permanent or catastrophic.
The Exxon Valdez spill occurred in an environment similar to the B.C. coast and is one of the most studied spills in history, Maki said.
"We did see recovery of most of those shorelines within two years following the spill," Maki told a hearing in Prince Rupert.
"Some of them had been very heavily oiled and had been subject to extensive cleaning. But within two years, we did have recovery of those ecosystems."
Oil was detected in the ocean floor, but forensic testing by the U.S. Environmental Protection Agency found the oil was due to natural seeps and degraded coal deposits, Maki said.
"The fact was the oil had ... biodegraded to simple compounds before they were deposited in the benthic sediments, and so the results of the tests ... showed that the sediments were not at all toxic," Maki said.
The federal panel is currently hearing testimony about the company's marine oil spill response plans.
Terri-Lynne Williams-Davidson, lawyer for the Council of the Haida Nation, questioned Enbridge experts about the impacts a marine spill would have on things like the razor clams that the Haida harvest commercially and the seaweed they dry and eat as a snack.
"It is a very important area to the Haida people," Williams-Davidson said, referring to the Gwaii Haanas National Park Reserve on the southern tip of the islands.
Miles away from Prince Rupert, across Hecate Strait and the proposed northern route of Northern Gateway tankers, she said residents of Haida Gwaii were listening to the hearings being broadcast live over the Internet.
On the remote islands, signs proclaiming opposition to the project are pervasive, nailed to hydro poles and fences and even spelled out on the roadside sign of a autobody shop.
Trevor Russ, vice-president of the Haida Nation, said the islands off the B.C. coast will bear the brunt of an oil spill.
"We have a mandate from our people going back a few years that we do whatever it takes to stop this pipeline project from going through," Russ said in an interview.
"The stand is very strong, in the Haida community and the non-Haida that reside on Haida Gwaii, are for the most part all opposed to the pipeline."
The company has said the odds of a tanker spill are one in 15,000.
"These are few and far between events," said Owen McHugh, a member of the Northern Gateway panel. "In 2012, there was no large oil spill anywhere in the globe. Tanker safety has improved to a level that is unprecedented."
But Environment Minister Terry Lake issued a statement Thursday evening, saying the government is still looking for solid evidence of the company's ability to prevent and respond to a maritime spill in a world-class fashion.
"Unfortunately, we're just not satisfied with the level of detail that Northern Gateway representatives are providing, and that makes it difficult to judge whether they are meeting B.C.'s conditions for supporting the project," said Lake.
Company officials made it clear under cross-examination that the actual spill-response plans will not be developed until the project has been approved, Lake's ministry added.
The panel has until the end of the year to produce a report and recommendations for the federal government, and the stakes are high.
A report released Thursday said the Canadian economy is losing $30-70 million a day because of the inability to get western Canadian crude to more diverse markets. The Alberta government recently warned of a $6 billion revenue shortfall this year.
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