Environmental groups say the government’s decision to approve a major pipeline will lead to the extinction of orca whales in B.C. waters.

On Tuesday, the Trudeau government gave the green light to the Kinder Morgan expansion project, meaning more than 400 oil tankers will navigate the Salish Sea.

“Today’s approval of the Kinder Morgan Trans Mountain project is the approval of the probable extinction of southern resident killer whales in the Salish Sea,” said Chris Genovali with the Raincoast Conservation Foundation.

Wildlife advocates say a major oil spill is inevitable, and with the southern resident orca population hovering around 80, it could be bad news for the marine mammals.

“It’s a dark day. Fortunately there are other species of whales in other parts of the world that haven’t been destroyed yet,” said Ken Balcomb, with the Center for Whale Research. “If people want to whale watch they’re going to have to go to those.”

Green Party Leader and Saanich Gulf Islands MP Elizabeth May’s reaction was equally swift.

“I have to say that I’m devastated by this decision,” she said.

May added that she’s willing to get arrested to stop the project.

“This is not a substance that can be cleaned up, no matter how fast your response time,” May said.

For wildlife groups like the Raincoast Conservation Foundation a major oil spill like the notorious Exxon Valdez is the biggest threat.

Other concerns include noise from increased tanker traffic, making it harder for the orcas to communicate, hunt and feed.

Groups like the conservation foundation are already considering legal action to try to stop the pipeline project.

“If the prime minister really believes that this is not a threat to the B.C. coast then he is misinformed,” May said.

With files from CTV Vancouver Island's Robert Buffam