Quebec's environment minister said Thursday his department had identified two companies responsible for the large number of dead fish that have been washing up in the Lievre and Ottawa rivers in western Quebec in recent weeks.
Benoit Charette said he issued a notice to Energie de la Lievre and Services Energie Brookfield in connection with the incidents.
He said in a statement the fish died as a result of dissolved gas supersaturation stemming from activities at the Masson hydro plant.
The Environment Department said a supersaturation occurs when the amount of dissolved gases in water is higher than normal, which can harm aquatic life.
Charette said the companies have been ordered to change their procedures at the plant to minimize supersaturation. They've also been told to inform the Environment Department if supersaturation levels surpass a specific threshold.
He is also requiring them to hire a recognized expert to study the issue and make recommendations to the government on what new rules and limits should be put in place.