Fish deaths caused by over-gasified water
Cause of death had been a mystery until now
OTTAWA — Quebec’s environment ministry says an oversaturation of gas in the water at a dam at Brookfield Hydroelectric Centre is to blame for causing waves of fish to die this summer.
Michel Rousseau, an assistant deputy minister for environmental control and dam safety, said Thursday that research by that ministry in recent weeks has shown that water flowing out from the dam into the Lievre River is too full of tiny air bubbles.
He said that when the fish swim in this bubbly water and filter it through their gills, it can cause them to die from a “gaseous embolism.”
Speaking to reporters on Thursday, Rousseau said Quebec’s environment ministry has ordered the plant’s operators at renewable energy corporation Evolugen to carry out an inquiry to determine the specifics of how the dam is causing the water to become too gaseous, and how to solve the problem.
In the short term, the ministry is also ordering the dam’s managers to take measures to reduce as quickly as possible the amount of gas being put into the water at the dam.
Quebec’s environment minister Benoit Charette said that it’s imperative that activities at the dam “be carried out with respect for the environment, and in this case, for the aquatic wildlife.”
“I am using measures at my disposal to do the maximum to ensure a return to normalcy in Gatineau,” he added in the provided statement in French.
The cause of the fish kill, which showed up en masse on Ottawa and Lievre river banks on July 8, 19, 29 and 31, had until now been a mystery, though Charette had said in previous comments that his ministry believed the Brookfield dam in Masson to be the cause.
On Thursday, Rousseau explained that other conditions in the water, such as temperature or content of bacteria or toxins, are not at levels that would normally cause fish deaths on this scale, and can thus be ruled out as causes.
Additionally, he said autopsies on the dead fish reveal several conditions consistent with oversaturation of gas in the water: namely, some of the fishes’ swimming bladders (a normally gas-filled organ) had burst through their mouths, and microscopic examinations had revealed tiny bubbles stuck to their fins.
In a written statement, Evolugen said the company is co-operating with the government and running the investigation.
“This is an unprecedented event not seen in our decades of operations. Evolugen remains committed to being a good steward of the environment, and will continue to be a good neighbour and partner for the community,” the statement said.
Evolugen also mentioned that “this spring’s extraordinary flooding and high water flows caused unusually high levels of debris in the Lievre River which has resulted in more frequent clearing of debris than the norm at our facility.”
But Rousseau has declined, for now, to draw a conclusive connection between flood debris and the water gasification.
“We know it’s coming from the centre, and they’re working to identify the cause,” Rousseau said on Thursday, seeming to defer to the inquiry. He confirmed that the waterways have seen more debris due to the floods, and that other cases of over-gasified water have had connections with flood debris.
This newspaper had reported that the respective Quebec and Canadian ministries in charge of the river had not been co-operating well in responding to the dead fish problem.
“We’ve been observing that the collaboration between all these government entities isn’t at its best,” said Patrick Nadeau, executive director of the Ottawa Riverkeeper. “One example of that is that the federal government, which has also sent enforcement officers looking into these exact same incidents … has also had to file access to information requests to get Quebec government lab data.”
Speaking on Thursday, Rousseau said Quebec’s ministry workers and scientists had operated as diligently as they could to investigate the dead fish crisis, including working through this past weekend to arrive at this week’s conclusion.