Pipelines are environmentalists’ favorite target lately, the most recent controversy bubbling up in Michigan over Line 5, a pipeline that transports about 23 million gallons of crude oil and liquid natural gas each day.

 The state hired top risk assessors, engineers and scientists to analyze the Enbridge Energy pipeline, also weighing alternatives. They found that the 64-year-old Line 5 “has never had a leak, and according to the latest assessment, is not at imminent risk of springing one,” the Detroit News opinion page reports.  In fact, it “could operate indefinitely without presenting an environmental risk.”

The state’s attorney general, Bill Schuette, is nonetheless rejecting the experts’ opinion. He wants the old pipeline shut down, replaced with a new, state-of-the-art tunnel to transport energy.

That’s an expensive infrastructure proposal, as MLive notes:

Building a new 30-inch diameter line across the straits in a tunnel would cost about $180 million in total costs, according to the study.

Closing and removing Line 5 from the straits would cost about $200 million and could cause propane costs in the Upper Peninsula to increase by 10 to 35 cents per gallon. The cost of gasoline at the pump in Michigan could rise by about 2 cents per gallon.

The Detroit News editorial board doesn’t write off the idea, but rightly says that “there’s no cause to be panicked into an expensive infrastructure project at this point.”

But green activists have taken a more radical—and alarmist—stance. Though experts say the old pipeline poses minimal environmental risk, they say it’s too dangerous. They’re also wholly opposed to a new tunnel and pipeline, which they also claim is a potential hazard.

The Detroit News sees their real motives:

The pipelines have become the favorite target of Michigan environmentalists, who fear a break in Line 5 would release petroleum products into the world’s largest source of freshwater.

… What’s at work here is not just a fear Line 5 will taint the lakes. The pipeline is primarily under fire because it carries fossil fuels. The carbon warriors will fight any solution for replacing Line 5, no matter how fool-proof.

Michigan should not play that game.

Indeed. Especially when the economic cost is significant, environmental changes need to be backed by solid scientific reason.