The Soo Locks in winter

Chris Albraugh, left, Steve Robbins and Josh Schwab work on a steam line in the Poe Lock, March 12, 2019. Steam will melt all ice and water in the lock and be drained prior to re-watering the lock on March 18.

Steam rises against a water gate in the Poe Lock as U.S. Corps of Engineers' Jeff Harrington inspects the ice cover. Steam is used to remove ice and snow from the dewatered lock, which has been without water for a 10-week winter maintenance and repair schedule.

The Poe Lock, 1,350 feet long, is empty of water, after repairs and maintenance wind down during a 10-week maintenance schedule.

U.S. Corps of Engineers chief of maintenance Jeff Harrington, left, and chief of operations LeighAnn Ryckeghen walk down into the Poe Lock Tuesday, March 12, 2019.

A winter maintenance work barge sits in the bottom of the MacArthur Lock Tuesday, March 12, 2019 in Sault Ste. Marie, Mich. A crane and other equipment were used for maintenance and repair over a 10-week shutdown of the facility. When water is added to the lock, the barge will be floated out to allow shipping to pass through.

U. S. Corps of Engineers Chief of Maintenance LeighAnn Ryckaghen views a water channel along the side of the Poe Lock. Four such tunnels allow water to move into and out of the huge lock as ships are raised or lowered in Sault Ste. Marie.

Two U.S. Corps of Engineers workmen drive scooters across a gate at the MacArthur Lock in Sault Ste. Marie. The electric scooters are used to move around the huge complex.

A U.S. Army Corps of Engineer, barely visible in his bright yellow safety coat, checks a drain at the bottom of the Poe Lock.

Two U.S. Army Corps of Engineers workers use small electric carts to move around the huge Soo Locks complex.

A 61-foot-high gate and the open channels for dewatering the Poe Lock in Sault Ste. Marie await de-icing March 12, before water is allowed back into the lock.