It’s hard to believe, but January 15 is right around the corner meaning, the Soo Locks will be closing for its annual winter maintenance. While the locks may lay dormant, workers will be hard at work making sure the vital pieces of infrastructure are ready to open in early spring on March 25. One of the rare sights that can only be seen during winter maintenance is the dewatering of the Soo Locks. This jawdropping draining doesn’t happen yearly, but the Poe Lock will be undergoing it this year.

While shipping is at a standstill, the strenuous United States Army Corps of Engineers winter work on the Soo Locks has made for some great photographs. We have been lucky enough to round up some great photos of winter work at the Soo Locks from year’s past.

This year, the MacArthur Lock closed early for the season in December for maintenance work including replacing gears that operating the lower gates and electrical system upgrades. The larger Poe Lock will remain open until the last ship passes through on Jan. 15. Then once closed, the chamber will be drained for work on its gates and sills. Also, the lock’s valves will be emptied and the drainage system cleaned. Safety inspections will be completed too. 

USACE Divers are a critical part of the dewatering process, opening underwater valves, inspecting drains and plugging leaks in the stop logs. 


Stop logs are lowered into place at the end upper end of the Poe Lock to help form a temporary dam to help drain the chamber. Each log spans the entire length of the 110 ft. wide lock and weighs 49 tons. Special equipment is required to place them.

Once the lock is empty equipment can be lowered down (looking west from the floor of the lock). Some years barges and tugboats are in the locks while they drain, and the dry lock serves as a dry dock for work and inspections on them.

Crowbars, shims, and a lot of brute force are needed to get the pintle (bolt) base out from under the gate.

After two-plus months of work is complete, water is let back into the lock.

Thank you to the U.S. Army Corps of Engineers at the Soo Locks for the assistance and photos for this blog. See more U.S. Army Corp of Engineers photos here. Can’t wait for the 2020 navigation season to get underway so you can get back to your regularly scheduled boat watching? Fret not, we have you covered. Join us at 11:30 p.m., March 24 as we prepare to welcome in the first ship of the 2020 season at the Soo Locks Park at midnight. 

The Stewart J. Cort was the first freighter to pass through the Soo Locks during the 2019 navigation season. The Cort made her way through the Poe Lock slightly after 12 a.m., March 25, 2019.

Even if it’s not a dewatering year, the hard-working men and women of the U.S. Army Corps of Engineers are doing maintenance work on the Soo Locks every winter. The observation deck will be closed but you’re always welcome to visit the Soo Locks Park 9 a.m.-6 p.m. daily and watch the work. Show your appreciation for all their hard work by sharing this blog on your Facebook or Twitter using #ilovethesoo. Be sure to follow us on FacebookTwitterInstagram, and Pinterest for more stories on the city you love so much!