If you take a stroll along the Welland Canal trails once winter sets in, the view is downright surreal... where massive 740-foot lake freighters churn all summer long, suddenly there is nothing but mud, bedrock, and empty air.
Every year around Christmas, one of North America’s busiest commercial shipping routes shuts down for the season. The St. Lawrence Seaway begins its annual "unwatering" routine, draining the canal reach by reach down to Lake Ontario—leaving the chambers bone-dry straight through January and February. But pulling the plug on a waterway that holds billions of litres of water isn't quite as simple as opening a drain in a bathtub...
The exposed floor of the Welland Canal during the winter maintenance shutdown.
Illustration by SCG NIAGARA
The Careful Drain: Why Engineers Can't Just Rush It
You might think workers simply open up the gate sluices and let gravity dump all that water into Lake Ontario overnight. In reality, Seaway operators have to throttle the drainage down to a crawl—strictly keeping the drop between 6.4 and 7.6 cm (2.5 to 3 inches) per hour.
