Construction equipment is seen on the floor of the Poe Lock, Tuesday, Feb. 21, 2023, in Sault Ste. Marie, Mich. The lock requires 22 million gallons of water to lift or lower a boat and is currently closed to March 25 for annual repairs. (AP Photo/Carlos Osorio, file)

SAULT STE. MARIE, Mich. — The Soo Locks will close to all marine traffic beginning 11:59 p.m. Eastern time Jan. 15, or until commercial traffic ceases, through 12:01 a.m. March 25 to perform seasonal critical maintenance.

The locks allo ships to navigate through what had once been rapids and a 22-foot drop between Lakes Superior and Huron. Located on the St. Mary’s River between Sault Ste. Marie, Mich., and Sault Ste. Marie, Ontario, the Soo Locks belong to a portion of the Great Lakes-St. Lawrence Seaway and are the busiest lock system in the world, handling more cargo tonnage than the Suez or Panama Canal.

Federal regulations establishes the operating season based on the feasibility of vessels operating during typical Great Lakes ice conditions.

Since the construction of the first lock in Sault Ste. Marie by the British in 1798, the Soo Locks have undergone numerous reconstructions and improvements. In modern day, winter is a time for essential maintenance.

“Every year, our lock and dam operators transition from assisting vessels through the Soo Locks to performing maintenance on the locks,” Operations Branch Chief Jeff Harrington said. “The team works alongside Soo Project Office maintenance crews to provide 100% effort in completing all critical maintenance during the ten-week shutdown. They work long hours in harsh northern Michigan winter conditions to complete a significant amount of maintenance during this annual closure period.”

The Poe Lock will remain operational on a 24-hour basis through Jan. 15 or until commercial traffic ceases, whichever occurs first.

During this winter’s maintenance period, the MacArthur Lock “will not be dewatered and will close for the season when the weather or ice conditions make operation unsafe and/or inefficient, or when the Poe Lock closes, whichever comes first,” the U.S. Army Corps of Engineers stated in a news release Tuesday. At least 48 hours notice will be given to those in the industry before the closure.

The team will install temporary panel bridges across the MacArthur and Poe Lock to provide the ability to mobilize materials and equipment to the job sites throughout the winter closure.

The Poe Lock will be dewatered during the maintenance season and is scheduled to reopen March 25.

Maintenance on the Poe Lock will include underfloor cleanout and manhole inspection, a five-year periodic assessment, Gate 1 repairs, Gate 4 lifting lug installation, Gate 3 jacking pedestal repairs and testing of Ice Study wall coating.

Maintenance on the MacArthur Lock will include the Soo Project Office fabricating and replacing spring boxes and lever arms for Gates 3, 4 and 5; constructing a recess cutout for the panel bridge; repairing a Gate 2 strut arm; and concrete and deck plate repairs to Gate 5. The MacArthur Lock is scheduled to reopen in late April.

In addition to the above, crews will also perform a wide range of other maintenance tasks from the replacement of pier fender timbers to inspections and preventative maintenance on electrical and mechanical systems on both the Poe and MacArthur Locks.

“Reliable Great Lakes navigation and the momentum of the American manufacturing supply chain depend on getting the job done here,” Soo Locks Operations Manager LeighAnn Ryckeghem said. “In an unforgiving northern climate, our exceptional team tackles the complex maintenance demands of aging infrastructure, proving their skill on systems well past their service life.”

More than 4,500 vessels, carrying up to 80 million tons of cargo, maneuver through the locks annually. Iron ore, coal, wheat and limestone are among the most frequently carried commodities. Opened in 1969, the Poe Lock is 1,200 feet long. The MacArthur Lock opened in 1943 and is 800 feet long.

The Poe and MacArthur Locks are the only two operational American locks at the Soo. The Sabin and Davis Locks are decommissioned; another lock for pleasure crafts is on the Canadian side.

The U.S. Army Corps of Engineers, Detroit District, maintains a navigation system of 81 harbors, including the Great Lakes Connecting Channels that join lakes Superior, Michigan, Huron, St. Clair and Erie.