Scott Eustis did not stop smiling for hours. The coastal wetland specialist with the Gulf Restoration Network was attending a public hearing in Baton Rouge. Its subject was a pipeline extension that would run directly through the Atchafalaya Basin, the world’s largest natural swamp. Eustis was surprised to be joined by more than 400 others.

“This is like 50 times the amount of people we have at most of these meetings,” said Eustis, adding that the proposed pipeline was “the biggest and baddest I’ve seen in my career”.

The company behind the pipeline, Energy Transfer Partners (ETP), had seemed to turn its attention to Louisiana just one day after Native American protesters thwarted the company’s Dakota Access project last month.

A spokeswoman for ETP, Vicki Granado, said the Bayou Bridge pipeline extension was announced in June 2015. If approved, the project will run though 11 parishes and cross around 600 acres of wetlands and 700 bodies of water, including wells that reportedly provide drinking water for some 300,000 families.

At the public hearing in Baton Rouge on Thursday, the first speaker, Cory Farber, project manager of the Bayou Bridge pipeline, said it was expected to create 2,500 temporary jobs. When Farber then said the project would produce 12 permanent jobs, the crowd laughed heartily.

“Those who have airboat companies and equipment companies that specialize in putting in equipment, they’re not opposed to pipelines because of the short-term jobs,” said Jody Meche, president of the state Crawfish Producers’ Association, one of dozens who spoke at the hearing.

“But once that pipe is in there, the jobs are gone.”

Once that pipe is in there, the jobs are gone Jody Meche

Other attendees applauded in favor of the pipeline, and former US senator Mary Landrieu of Louisiana, a supporter, was in attendance. But Native Americans also dotted the crowd, many of them fresh from Standing Rock.

“The Native Americans in North Dakota get a lot of credit for showing people their power,” Eustis said.

Protester Cherri Foytlin, organizer of the pro-sustainability Bridge the Gulf project, brought her teenage daughters, Jayden and Erin. In November, Erin and 20 other kids from around the country filed a lawsuit against the federal government for ignoring climate change. The suit will soon go to trial.

Meche not only makes his living in the Atchafalaya Basin, but he also calls it home. Where most in attendance worried about potential oil spills and their effect on drinking water, Meche was more concerned with ways existing pipelines have, he said, “crippled” the fishing industry.

“They excavated the trench that they put the pipe in and then [they didn’t clean up] and it leaves a dam behind that blocks the water flow,” he said on the microphone, “until there’s not enough oxygen in the water for the crawfish, the fish, or anything.”

If approved, the project will run though 11 parishes and cross around 600 acres of wetlands and 700 bodies of water, including wells that reportedly provide drinking water for some 300,000 families. Photograph: Alaina Dunn​​​​​​​​​​​​​​​​​​​​​​​​​​

Meche said these left-behind “spoil banks” also disintegrate and slip down into the interior of the swamp, filling it with silt. “Areas that were 8ft deep 20 or 30 years ago are now a hill,” he claimed, adding that it all increases flood risk to boot. After his three minutes were up, he left the microphone, breathing heavily.

Debate was fierce. Pro-pipeline speakers – oil industry reps, state representatives, a retired Louisiana State University professor – pointed out that many pipelines already run through the Atchafalaya Basin and said pipelines were in general the safest way to transport oil – in the case of the Bayou Bridge pipeline, 280,000 barrels per day of crude to the Gulf coast region, with the potential for 480,000.

At a pre-hearing teach-in outside in the long shadow of Baton Rouge’s capital building, Anne Rolfes and her Louisiana Bucket Brigade activists repeated how pipelines caused 144 accidents in Louisiana alone last year.

Pipeline supporters countered by citing a Frasier institute study from 2015 that said rail transport of oil was more than 4.5 times more likely to experience an accident than pipelines, and that 99% of pipeline accidents from 2003 to 2013 did not damage the environment. Pipeline PR materials also say pipelines are cleaner and more environmentally safe than rail transport because they don’t burn fossil fuels.

ETP’s new pipeline plans also acknowledge the need to deal with spoil banks, and include a suggested post-construction initiative to improve water quality and flow to the basin.

If he thought this was true, Meche said, he would support the idea. “I have no problem with the pipeline if they do it right,” he said. “I do like my oil and gas.”

100,000 people were displaced from their homes because of climate change – I guess we’re finally just sick of this Scott Eustis

He just suspected that ETP would not go the extra mile. “You know how much money you’re talking about, bringing tractors back in the basin to fix all that? They’re only going to pay what they are obligated to do, and nothing else.”

Rolfes also scoffed at oil industry promises. “The best way to determine the future is to look at the past,” she said. “And you can see how honest they were about filling the old canals: there’s not a single example of them fixing the existing spoil banks.”

At least, as activists see it, Louisiana residents are starting to really care about environmental issues and, more importantly, to make themselves heard.

“A lot of times we don’t get this opportunity to speak up,” said Eustis, still admiring the surprisingly large crowd. “[These oil companies] want to just roll over us.

“But after Katrina, and the BP spill, and the Baton Rouge flood last year – 100,000 people displaced from their homes because of climate change – I guess we’re finally just sick of this.”