Mystery solved: Hydro plant blamed for fish deaths

The Quebec government found a h​​​ydroelectric dam plant is responsible for the wave of dead fish this summer.

Hundreds of dead fish found washed up along Lièvre, Ottawa rivers this summer

Residents began noticing dead fish along the Lièvre and Ottawa rivers in early July. (Lorian Belanger/CBC)

A hydroelectric plant on the Lièvre River is to blame for the mysterious deaths of hundreds of fish this summer, Quebec's Environment Ministry revealed Thursday.

A ministry investigation found operations at the plant in Masson-Angers, in Gatineau's east end, resulted in over-saturation of dissolved gas, or air, in the Lièvre River.

That led to the death of the fish, many of which floated into the nearby Ottawa River, the ministry said.

The government is ordering the companies that operate the plant, Lièvre River Power L.P. and Brookfield Power Services Inc., to fix the problem and continue monitoring dissolved gas levels to ensure they don't endanger aquatic life.

The operators will also have to hire an expert to "identify the operating conditions of the dam that are likely to cause the phenomenon in question," and comply with the expert's recommendations.

Charges, fines possible

In a statement, the vice-president of public affairs and sustainability for Evolugen, the new name for Brookfield Renewable Canada, appeared to blame the problem on this spring's flooding.

"This spring's extraordinary flooding and high water flows caused unusually high levels of debris in the Lièvre River, which has resulted in more frequent clearing of debris than the norm at our facility," Vanessa Pilotte wrote.

It's not immediately clear what the clearing of debris has to do with the discharge of dissolved gas flagged by the ministry.

A dead carp is seen washed up near a boat launch in Gatineau, Que.'s, Masson-Angers sector on Aug. 1, 2019, just metres from where the Lièvre River joins the Ottawa River. (Kimberley Molina/CBC)

The investigation into the incident is ongoing and the company is co-operating with all levels of governments, Pilotte said. 

Michel Rousseau, Quebec's assistant deputy minister for the environment, said charges and fines are possible. 

Fish deaths began in July

Starting in July, some 2,000 fish carcasses in four distinct waves were found floating in the Lièvre and Ottawa rivers.

Further investigation determined the fish were coming from the Lièvre River, which flows into the Ottawa River across from Cumberland, Ont., just past Ottawa's eastern city limits.

The first wave was recorded July 8, with more on July 19, July 29 and July 31.

Last month, the Quebec government said their analysis pointed to a toxic spill, but at that time couldn't identify the source.

After the fourth wave of fish deaths in early August, the ministry turned its attention to a hydro dam on the Lièvre River.


To encourage thoughtful and respectful conversations, first and last names will appear with each submission to CBC/Radio-Canada's online communities (except in children and youth-oriented communities). Pseudonyms will no longer be permitted.

By submitting a comment, you accept that CBC has the right to reproduce and publish that comment in whole or in part, in any manner CBC chooses. Please note that CBC does not endorse the opinions expressed in comments. Comments on this story are moderated according to our Submission Guidelines. Comments are welcome while open. We reserve the right to close comments at any time.

Become a CBC Member

Join the conversation  Create account

Already have an account?