The only way in and out of Lake Superior for most shipping traffic closed Monday morning for several hours of emergency repairs, giving urgency to the push for a new large lock at Sault Ste. Marie, Mich.

The Poe Lock, the largest of the Soo Locks and the only one capable of handling the large lake ships that carry Minnesota iron ore, reopened late afternoon, according to the Lake Carriers’ Association.

“When I started at Lake Carriers 15 years ago this never happened. Now it happens once, maybe twice a year,” said Jim Weakley, president of the association. “The 50-year-old lock is starting to show wear and tear.”

The Army Corps of Engineers considers the passage a “single point of failure in our nation’s iron ore supply chain.” Construction on a new $922 million lock is expected to start next year, but it won’t be done until 2026 at the earliest and could take to the end of the decade, depending on future appropriations from Congress.

“It’s still a slow slog, but we’re past the critical point of making sure it’s fundable,” Weakley said.

The new lock would mirror the Poe at 1,200 feet long, 110 feet wide and 32 feet deep. The Army Corps of Engineers is expected to award a channel-deepening contract this fall for the new one.

About 80 million tons of cargo pass in and out of Lake Superior through the Soo Locks every year.

“It’s such a key gateway, not just for the rest of the Great Lakes but the rest of the world,” said Jayson Hron, spokesman for the Duluth Seaway Port Authority. “A 12-hour delay seems brief, but it is imperative that vessels are able to make the most out of every minute they have out there.”