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The Soo Locks will open with the official start of the main shipping season on the Great Lakes.

But somebody’s got to break the ice first.

Mike Davanzo is the Commanding Officer of the U.S. Coast Guard Cutter Mackinaw. We caught up with him on the icebreaking ship.

“I am on the bridge of the Mackinaw and we’re breaking the ice on the upper approaches of the Soo Locks in preparation for lock opening.”

When the locks open, ships known as salties can come into the Great Lakes from foreign ports.

“The St. Lawrence Seaway will open up on the 22nd of March, and then once that opens up the salties will start coming in and then the Soo Locks will open on the 25th and the whole region will be open to traffic as we clear the waterways of the ice.”

Some people have tossed out the idea that our warming climate could change the length of the shipping season. Over the years, there’s been less ice on the Great Lakes because the lake water has been warming. Researchers at the National Oceanic and Atmospheric Administration have found that ice cover has declined more than 70 percent on the Great Lakes since 1973.

Glen Nekvasil is the vice president of the Lake Carriers’ Association. It’s a trade group for the vessel operators on the Great Lakes that fly the U.S. flag.

I asked him what he thought about the possibility of a longer shipping season.

“Let’s not go retiring our Coast Guard icebreakers, you know what I mean? But the length of the navigation season is something that could be looked at.”

The Lake Michigan-Lake Huron system has hit record low water levels. Nekvasil says that has serious consequences.

“Water levels are critical to our industry. Depending on the size of your vessel, you lose anywhere from 50 to 270 tons of cargo for each inch of draft. So at the end of last season, our biggest ships were losing more than 10,000 tons of cargo each trip.”

He says because of antitrust laws, trade associations can’t have knowledge of freight rates, but he says it’s clear that carrying less cargo has economic implications.

“When they’re not carrying cargo, that means less revenue, and that means less ability, less financial resources for them to maintain and modernize their vessels. But really, the most important question here is the companies and the industries that we serve. The steel industry in this country still generates more than 200,000 jobs, and you cannot make steel without iron ore. And most of the iron ore that American blast furnaces use is mined in Minnesota and Michigan and shipped on the Great Lakes. Same thing with the coal for power generation, the limestone for the construction industry. These cargos support a lot of jobs.”

I asked Nekvasil if there’s a point where water levels could dip so low that it would no longer be feasible to transport materials and goods on the lakes.

“There’s a point where number one, it would no longer be economically feasible to operate the vessels – I mean, it still costs just as much money to carry 60,000 tons as it does 70,000 tons. You also reach a point where the vessel isn’t low enough in the water to be safely operated. That’s the reason why we no longer take coal to Dunkirk, New York. There just isn’t enough water in the harbor now to fully submerge the propeller and the rudder, so it would not be safe for the vessel to try to enter the harbor.”