A controversial plan to dig a tunnel under the Great Lakes in order to replace aging oil and natural gas pipelines was given the final go-ahead Wednesday, Crain's Detroit reported.

The Mackinac Straits Corridor Authority, created just last week by outgoing Gov. Rick Snyder, approved a deal between the state of Michigan and the Canadian company Engridge to replace its aging Line 5 pipelines with the tunnel, which will be drilled into the bedrock beneath the Straits of Mackinac connecting Lakes Huron and Michigan.

Environmentalists and indigenous groups criticized the decision and the process that led to it, which they say was rushed through during a lame-duck legislative session despite the fact that incoming Democratic Gov. Gretchen Whitmer and Attorney General Dana Nessel both promised to shut down the 65-year-old Line 5 pipelines during their campaigns

"We debated on whether to even come today to give legitimacy to this," Mike Ripley of the Chippewa Ottawa Resource Authority said at the meeting at which the decision was announced, as Michigan Radio reported. "We don't think this is a legitimate board, and we're very concerned about the undemocratic process in the last month that's gone on in the lame duck Legislature in Michigan."

The council approved the tunnel after only a five day comment period, and one of its three members was only appointed three days before Wednesday's meeting. At the meeting, 51 people spoke, with roughly equal numbers opposing and supporting the tunnel, but critics said the debate was a "sham" because the bill Snyder signed creating the panel also mandated that it approve the tunnel if it met certain criteria also outlined in the bill.

Some unions and Enbridge employees spoke in favor of the tunnel, saying it would provide jobs and be less likely to cause oil spills than the existing pipelines, which critics are worried will rupture, contaminating drinking water and even polluting the Lakes' shoreline. Snyder echoed those supporting arguments in his remarks following the decision, as Craig's Detroit reported.

"Today's actions will result in the removal of the oil pipeline from the bottom of the Straits of Mackinac, maintain critical infrastructure connections between our peninsulas, provide energy security for residents of the Upper Peninsula and northern Michigan and create good-paying jobs," Snyder said.

But the National Wildlife Federation said in a statement ahead of Wednesday's meeting that the deal with Enbridge failed even the one environmental promise Snyder had made, since it allows the aging pipelines to run indefinitely while the tunnel is being built and allows the company generous leeway to delay construction in the case of various events.

"This backroom deal sets no end date for the twin pipelines currently sitting in the open waters of the Great Lakes. The Snyder administration is trying to disguise the status quo as progress," National Wildlife Federation Great Lakes Regional Center Conservation Partnerships Manager Beth Wallace said.

Opponents also expressed concern about locking the state into building new fossil fuel infrastructure as scientists warn that humans need to rapidly reduce greenhouse gas emissions in order to effectively combat climate change.

"We know we need to soon be transitioning away from fossil fuels and towards cleaner alternatives," Petoskey, Michigan resident Frank Hawthorne said, according to Michigan Radio. "How then, is an expensive Straits tunnel, which is likely going to cost much more and take far longer to build than estimated, how is that sending anyone the message that Michigan is a forward-thinking and acting leader in responding to the challenges of the future?" Hawthorne asked.