The Trudeau government's approval of the Kinder Morgan Trans Mountain pipeline expansion is meeting fierce opposition in B.C., including a vow from the Tsleil-Waututh First Nation that this is "the beginning of a long battle" to stop the project.

Prime Minister Justin Trudeau announced the decision in Ottawa today, saying the project would give "much needed new hope" to thousands in Alberta and provide $4.5 billion in federal and provincial government revenue.

"If I thought this project was unsafe for the B.C. coast, I would reject it. Period," said Trudeau. "This decision was based on debate, science and evidence."

It's a move that opponents of the project saw coming — with Trudeau announcing improved oil spill response capacity earlier this month.

Protests greeted that announcement and have escalated since with thousands joining one demonstration.

Thousands of protesters gathered in front of Vancouver City Hall to protest the Kinder Morgan Trans Mountain pipeline on Nov. 19, 2016. (Tina Lovgreen/CBC)

"I'm not surprised ... I'm sincerely disappointed," said Charlene Aleck, a councillor with the Tsleil-Waututh First Nation, whose traditional territory includes Burrard Inlet which would see a massive increase in tanker traffic if the project goes ahead.

"This is not just our backyard, this is literally in our kitchen ... It's definitely the beginning of a long battle ahead for us."

Kinder Morgan does have some Indigenous support for the project, but as of last week, had gathered letters of support from only about one-third of the 120 Indigenous groups it consulted.

The project would expand an existing 1,150-kilometre pipeline between the Edmonton area and Burnaby, B.C. It would create a twinned pipeline increasing the capacity of the system from 300,000 barrels per day, to 890,000 barrels per day.

The route of the proposed Trans Mountain pipeline. (Canadian Press)

'Defining moment' says Kinder Morgan

Kinder Morgan, the B.C. Chamber of Commerce and Greater Vancouver Board of Trade are cheering the decision, with the company calling it a "defining moment for our project and Canada's energy industry."

In a statement, the president of Kinder Morgan Canada said the project has "evolved substantially" as a result of scrutiny and community input.

"We're confident we will build and operate this project in a way that respects the values and priorities of Canadians," said Ian Anderson in a statement.

The company is continuing to seek necessary permits, with a plan to begin construction in Sept. 2017 and start using the twinned pipeline in late 2019.

"We feel a good decision has been made," said Dan Baxter of the B.C. Chamber of Commerce. "We're very, very happy for that."

In a statement, the B.C. Chamber said the pipeline approval reaffirms B.C.'s reputation as a jurisdiction that is open to investment and will help open up Canadian oil to international markets.

The Greater Vancouver Board of Trade said the project will generate more than a billion dollars in construction spending for the region and create thousands of high-paying jobs.

A ship receives its load of oil from Kinder Morgan's Westridge loading dock in Burnaby, British Columbia, on June 4, 2015. (Jonathan Hayward/Canadian Press)

Risks to coastline, whales and climate

Opponents of the project have warned the expanded pipeline and tanker traffic brings increased risk of an oil spill that could hurt the region's economy, in addition to concerns about wildlife and carbon emissions.

Vancouver has estimated a Kinder Morgan pipeline spill could cost the city $1.2 billion to clean up, and today Mayor Gregor Robertson said he was "profoundly disappointed" by the federal government's approval.

"Approving the Kinder Morgan project flies in the face of precautionary, evidence-based decision-making and takes Canada in the wrong direction on climate change," said Ecojustice lawyer Karen Campbell in a statement.

Ecojustice, along with clients including the Raincoast Conservation Foundation, said the impact of tanker noise on a very endangered — and legally protected — population of orcas on the B.C. South Coast could be deadly.

"Today's approval of the Kinder Morgan project sanctions the probable extinction of southern resident killer whales," said Raincoast executive director Chris Genovali in a statement.

The groups are considering their legal options to fight the approval.

A 20-year-old male from the southern resident population of killer whales, which only includes about 80 individuals. (Dave Ellifrit/Centre for Whale Research)

Battle could be heading to court

For the Tsleil-Waututh, the next battle over the project may also be the courts, said Aleck.

"We have a right to steward our land, and that is upheld," she said.

Indeed, the end of Enbridge's Northern Gateway project — officially rejected today — arguably came last summer, when the Federal Court of Appeal overturned Northern Gateway's approval for failure to properly consult First Nations.

"What I've said for quite a long time is the strongest legal and political opposition [to pipeline projects] was First Nations' rights in court. And that did kill the Northern Gateway pipeline project," said George Hoberg, a University of B.C. professor in environmental and natural resource policy.

"Whether or not it will kill the Kinder Morgan project is less certain."

Hoberg is concerned by the Trans Mountain pipeline's approval, and doesn't think it has social licence in B.C. to proceed.

But, he says the courts may have a different view with this project than Northern Gateway, because Trudeau's government has learned from the Harper government's mistakes when it comes to First Nations consultation.

"What we don't know is if the different, more careful approach will meet the standards for consultation and accommodation required by the courts."