VANCOUVER—The risks posed to declining salmon populations by a diluted bitumen spill in the Lower Fraser River weren’t adequately considered by Trans Mountain before the pipeline expansion project was approved, says a new report by a B.C.-based conservation group.

The report, co-authored by an independent toxicologist and two Raincoast Conservation Foundation biologists, outlines “serious deficiencies” with the company’s spill risk assessment.

Trans Mountain failed to consider the “complexities” of the river, including log booms and other infrastructure, meaning the estimated volume of oil that could be stranded by these objects was underestimated, it says. Similarly, the company did not address the potential for submerged or sunken oil.

Salmon are “ubiquitous in the Fraser River” and “an iconic species as far as B.C. is concerned,” said Kate Logan, one of the report’s authors and an independent biologist. She wants the federal government to acknowledge the extent of what isn’t known about the risks of a diluted bitumen spill.

The Trans Mountain pipeline expansion project would essentially twin the existing 1,150-km pipeline, triple the flow of oil, and result in a sevenfold increase in tanker traffic to the terminal in Burrard Inlet.

Along with other petroleum products the pipeline will carry diluted bitumen, or dilbit. According to the Raincoast report the most common dilutant used to create dilbit in Alberta is condensate, described as “a petroleum by-product composed primarily of very light, highly flammable, and acutely toxic components.”

While the federal government has said the pipeline expansion is in the national economic interest, critics are worried about both the climate impacts of increased greenhouse gas emissions and the environmental repercussions of an oil spill.

In a statement a spokesperson for Natural Resources Canada said the project went through “the most rigorous federal regulatory review and consultation on a major project in Canadian history,” and was approved subject to 157 conditions meant to protect the environment.

Ahead of the federal approval Trans Mountain modelled spills of between 1,250 and 2,700 cubic metres in the Athabasca River, North Thompson River and the Fraser River, according to the National Energy Board’s May 2016 recommendation report.

Models of a 1,250-cubic-metre spill downstream of the Port Mann Bridge from an on-land pipe failure showed most of the oil — 74 per cent — would become trapped on shore. Between 25 and 35 kilometres of shoreline would also be affected, depending on the season, and could reach as far as the Gulf Islands and into Boundary Bay.

The company found that the level of suspended sediments and turbidity in the Lower Fraser aren’t high enough to make it likely that oil droplets would bind to sediment and sink, the energy board report notes.

In a statement, a spokesperson for Trans Mountain said, “pipeline safety is our number 1 priority and, through the experience gained in the past in 65 years, Trans Mountain has developed a mature suite of programs to prevent pipeline failures and maximize the safety of the pipeline system.”

The company added that it has prepared “extensive” response plans to help emergency responders react more quickly and effectively to limit the potential impacts of a spill.

The statement went on to say that “diluted bitumen, its properties, transportation and cleanup of spills, has been studied for many years by third parties in Canada and the U.S. including the National Research Council of Canada and the Government of Canada.”

A spokesperson for Natural Resources Canada added that the federal government has been studying oil spills for decades and is continuing to investigate the behaviour of dilbit.

The government is also working to establish new and stronger international collaborations to ensure Canada has access to the best knowledge worldwide, the statement said.

But despite industry and government assurances, there are a lot of unknowns about the potential impact of a dilbit spill in the Fraser or another one of the roughly 250 salmon-bearing streams the pipeline will cross, Logan said.

Since January 2016, there have been 155 spills along NEB-regulated pipelines. Thirteen of those were oil spills that resulted in a total of 1,127 cubic metres of oil being spilled.

A dilbit spill in the Lower Fraser or one of its many tributaries could be “catastrophic” and destroy critical spawning habitat, the Raincoast report says, adding further pressure to salmon populations already struggling.

The report notes a third of the salmon populations in the Fraser are considered at-risk of extinction.

“Juvenile and adult salmon can be exposed to spilled oil via oil droplets in the water column, toxic components of oil that have dissolved in water, and through consumption of contaminated prey.

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“However, embryonic fish (developing inside the egg), are most at risk because critical development is occurring at a rapid rate, and the embryos themselves are immobile and unable to escape exposure,” it says.

“For salmon embryos that do survive, exposure to oil can cause impaired heart function, physical deformities, reduced growth, and compromise their ability to produce offspring.”

Dave Scott, a Raincoast biologist and another of the report’s authors, said salmon are already experiencing detrimental effects of climate change.“We don’t think it’s a great time to be adding more threats when we’re trying to recover these really important species,” he said.

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