Lake outflows ‘pushing the limits of system’
Shipping officials try to stave off flooding while maintaining Seaway navigation
Last spring’s rainfall has forced record-setting water outflows from the Great Lakes, and with levels in Lake Ontario still high, there is no end in sight, says the International St. Lawrence River Board of Control.
“Right now, Lake Ontario outflows are at maximum values — the highest they’ve ever been for a sustained period,” explained Jacob Bruxer, a senior water resources engineer for Environment and Climate Change Canada and member of the board.
The board announced Tuesday that outflow is at 10,400 cubic metres per second, which Bruxer said is the highest that has been recorded dating back to the 1900s.
“We’re already really pushing the limits of the system,” he said. The outflow rate has been at this level since June 14.
“We’re trying to provide relief to those affected by high waters on Lake Ontario right now by maintaining this high outflow,” said Bruxer, adding that there is no set date for when flow rates might decrease.
“Certainly around the next few weeks, they’ll be quite high.”
The goal of these efforts has been to strike a balance between lowering the levels of Lake Ontario, not causing more floods in Quebec, downstream of the lake, and maintaining navigation, said Chad Allen, director of operations at the Shipping Federation of Canada.
“It’s been challenging,” Allen said, but mitigation efforts put in place by the St. Lawrence Seaway Management Corporation, such as a tugboat at the Iroquois Locks about 60 kilometres south of Cornwall, Ont., have helped ensure continued commercial navigation.
Allen said they haven’t seen any loss in business due to the water levels.
Another mitigating measure has been lowered speed limits on the waterways to reduce wakes (the waves created by a passing vessel), said Andrew Bogora, spokesperson for the St. Lawrence Seaway Management Corporation.
But their focus hasn’t been on commercial navigators, he said. Rather, their main concern has been reducing the impact on surrounding shorelines and communities, Bogora explained.
That is also why increased outflow won’t be considered any time soon, even for short periods, Bruxer explained. A rapid increase in flow could pose a threat to the shoreline of the St. Lawrence River and other critical areas.
“Those changes in conditions could really eat away at the shoreline,” he said. “(Erosion) is a natural process, but when you’re talking about doing things unnaturally, like varying the flow on purpose repeatedly, it can cause ecological impacts.”