The Ministry of Environment for Quebec says the public should be rest assured the fish deaths are not the result of a chemical spill.

A spokesperson for the ministry tells CTV News there is an open investigation into the ‘operations’ of the Brookfield Hydro Plant located on the Lièvre River.

“The most plausible cause of fish deaths would be related to the Brookfield Hydroelectric Plant Operations,” said ministry spokesperson and Outaouais Environmental Control Centre regional director Alexandre Oullet.

“There is not evidence of a chemical source or a chemical spill.”

The ministry however did not specify why Brookfield is under investigation, or what led them to that theory, citing the integrity of the investigation.

The Ottawa Riverkeeper however says that hypothesis only brings more questions, not answers.

“They have yet to advise the dam operators on what precisely they are suspecting here,” said Patrick Nadeau, the executive director of the Ottawa Riverkeeper.

“If it is them, they do not know the problem at this point so they cannot take action to prevent a fifth fish kill event.”

Nadeau says more communication is needed among all levels of government and with the Brookfield Hydro Plant.

“How exactly would the dam kill these fish, not once, not twice but four times?”

“Quebec Environment and Climate Change Ministry officials confirmed to us this afternoon, that the investigation continues to consider all facilities and operations around the river but provided no additional information to us at this time. We will continue to collaborate with all governmental authorities on this matter.” said a spokesperson for Evolugen, the company that runs the plant, said in a statement to CTV News Friday.

There have been four waves of dead fish in a month, with the latest batch discovered Wednesday night. More than 1000 fish were found dead Monday.

Acute intoxication was to blame for the first two waves of dead fish, and according to the Ottawa Riverkeeper, it is also to blame for the third incident.  

It is not an infectious disease, but rather the fish were exposed to something toxic in their environment. However, the cause still remains unknown.

According to Quebec's Ministry of Forests, Wildlife and Parks, a team travelled to the Masson-Angers area and took fresh water samples Samples for analysis were sent to the Quebec Centre for Wildlife Health in Saint-Hyacinthe.