to come to fruition, Whitmer urged Ebel to explore  alternative solutions  to replacing the aging pipeline that could potentially be months away, rather than years.

 The choice is not simply between the existing pipelines and a tunnel. Multiple energy supply-chain experts have concluded that, with sufficient notice and an orderly transition, the market can adapt to a Line 5 shutdown without significant supply shortages or price spikes,  she wrote.  I am calling on Enbridge to pursue an alternative to both the existing dual pipelines and the tunnel, and to begin that work now. 

Officials and environmentalists have been trying to shut down the pipeline for years over concerns that it could harm the Great Lakes, which holds about 21% of the world's fresh surface water.

The lakes also supply drinking water to more than 40 million people and support a $9.3 trillion regional economy, Whitmer said.

Michigan tribal leaders have been particularly outspoken about the risks Line 5 poses.

On Thursday, Four Tribal Nations in Michigan petitioned state regulators, challenging two other environmental permits approved by the state in hopes of overturning them as well.

 For generations, we have warned about the danger Line 5 poses to the Straits of Mackinac and the catastrophic consequences a spill could have for our waters, our fisheries, and our way of life,  said Bay Mills Indian Community President Whitney Gravelle, who called the latest action from the state  an important step.   The Straits are our homeland, not a corridor for a foreign oil company. We do not own the Great Lakes. We are borrowing them from future generations, and it is our responsibility to return them whole.