The latest plan to protect Lake Michigan from a horrendous oil spill might work just fine — as long there’s no ice and the waves don’t get too rambunctious.

We’re sure you spotted the catch already. At this time of year, thick ice often covers parts of Lake Michigan. And big waves aren’t exactly a rarity on the Great Lakes.

EDITORIAL

The source of worry is the 65-year-old mussel-encrusted Enbridge pipeline, which runs along the floor of the Straits of Mackinac at the northern tip of Lake Michigan and which has 4.5 miles of mostly exposed pipeline, some of which is losing its protective coating.

In December, Enbridge finally agreed to temporarily shut down the pipeline whenever waves reach eight feet or taller, to prevent a leak from occurring when waves are so high that containing spilled oil on the surface would be difficult. Enbridge also agreed to explore replacing the pipeline with a tunnel under the lake and to report back with more information by August.

But Enbridge would still pump oil through the line, which is split into two separate pipes as it goes under the straits, when ice forms over the lake that’s so thick only an icebreaker could get through it. And how many icebreakers are kept on hand for just such an emergency? None. The icebreakers on the lakes mostly clear lanes for freighters and might be two days away when oil starts to spill. Up to 23 million gallons of oil are pumped through the pipeline each day.

Environmentalists worry that waves of, say, even seven feet would make it too difficult for boats to contain an oil spill in an area with such powerful currents, leading to an ecological disaster. They think Enbridge should shut down the pipeline once waves get taller than three feet.

If the pipeline, called Line 5, springs a big leak, 700 miles of Lake Michigan shoreline would be vulnerable to fouling. Drinking water for thousands of people could be tainted. The commercial fishing, tourism and boating industries would take a hit. And the damage could stay with us for decades, both in Lake Michigan and Lake Huron, which is on the other side of the Straits of Mackinac.

Last week, U.S. Rep. Mike Bishop, R-Mich., proposed a bill that would mandate frequent reports on the condition of pipelines in and around the Great Lakes, saying “One of the largest threats facing our Great Lakes is an oil spill.”

Shutting down the pipeline wouldn’t be simple. It’s part of a network that transports oil to 21 refineries, and it also carries natural gas and propane. All that fuel needs to get to its destination.

But we don’t need an ecological ticking time bomb at the most vulnerable spot of Lake Michigan. What’s needed is a solution that decommissions the exposed pipeline and doesn’t put other communities at risk.

Send letters to letters@suntimes.com.