Manitoba opponents were quick to express their disappointment and frustration Tuesday evening after Justin Trudeau announced the approval of two oil pipelines in western Canada.

About 20 protesters gathered at the corner of Portage Avenue and Main Street at around 9 p.m. to show their disapproval of the pipeline.

"I'm absolutely disgusted with the decision," said Cecil James, a band councillor for Roseau River First Nation.

He said with cleaner technologies it's time to keep the oil in the ground. However, if the pipelines go ahead, he believes there will be demonstrations and protests like Standing Rock, where thousands have been camped out at the North Dakota reservation for months to oppose the Dakota Access pipeline.

"People are going to put their bodies on the line to stop these pipelines from going through," he said.

Assembly of Manitoba Chiefs Grand Chief Derek Nepinak said that when discussions first started it was a process of manufacturing consent rather than getting true permission. While he was disappointed, Nepinak said he wasn't surprised.

"It's been lip service to a process that would require a great consensus amongst Indigenous people and there is no consensus. As was said, governments provide permits but communities provide permission," Nepinak said.

Indigenous leaders from across the country, including Nepinak, watched the announcement in Winnipeg after wrapping up the first day of a conference on climate change and the environment with guest speaker David Suzuki.

Nepinak said governments and businesses must realize they cannot undertake projects in Indigenous territory without full consent.

"[The Liberal government] is not going to earn consent on a future that includes tar sands expansion because it's the wrong choice. It's not good for Canadians," Nepinak said.

20 of 63 Manitoba chiefs signed on to the growing Treaty Alliance against Tar Sands Expansion, a group pledging to fight oil sands and pipelines. (CBC) Mitchell Van Ineveld, a member of the Manitoba Energy Justice Coalition and an organizer with Divest UWinnipeg, said the upstream greenhouse emissions on the extraction alone completely offset all of Trudeau's environmental initiatives announced so far.

"This is really a worst case scenario. These pipelines completely blow our climate commitments out of the water," Van Ineveld said.

Van Ineveld is part of the group that occupied Natural Resources Minister Jim Carr's Winnipeg constituency office earlier this month. He said Tuesday's decision is a reversal on commitments from the government regarding the environment, international agreements and to nation-to-nation building within the country.

Van Ineveld said he expects enormous public outcry in response.

"I think we're going to see a Standing Rock style mass civil disobedience in B.C., but probably also in Manitoba, probably also in Alberta," he said.

"Anywhere on the paths of these pipelines I think we're going to see enormous groups of people physically obstructing the construction. I don't think these projects are going to get built."

Not all Manitobans oppose pipelines

Some in western Manitoba's oil country are embracing the Trudeau government's approval of the Enbridge's Line 3 replacement pipeline.

Roughly half the property tax revenue in the rural municipality of Pipestone comes from the oil and gas industry. Reeve Archie McPherson said he was happy to learn that the pipeline, which runs through his municipality, will almost double.

"Any time you can add to the economy — any place in Canada, especially western Canada — with extra jobs and extra revenue for the oil companies, it's a positive," McPherson said.

Nepinak said that the National Chief of the Assembly of First Nations Perry Bellegarde has been invited to the first ministers meetings next week in Ottawa and that Bellegarde will have an opportunity to make a submission.