Yamaska River sewage dump under investigation after thousands of fish die

Quebec's Environment Ministry says it did not authorize the dump of 8,000 tonnes of raw sewage by the City of Saint-Hyacinthe that experts and local officials believe led to the deaths of thousands of fish in the Yamaska River.

Ministry spokeswomanMylneGaudeau said the provinceis now investigating.

• Saint-Hyacinthecould be to blame for thousands of dead fish in theYamaskaRiver
• Fish are dying by the thousands in theYamaskaRiver and no one knows why

The city carried out the dumpon June 28in connection withexpansion work on the city's wastewater treatment plant.

I can tell you I'm very disappointed and troubled by what happened.- ClaudeCorbeil,Saint-Hyacinthe mayor

Several days later, after following up on concerns from residents, provincial authorities foundthousands of fish on the bottom of the river,discoloured and in an advanced state of decay.

"Theinquirywill allow us to determine if any laws were broken," Gaudreau said.

City Coun.DonaldCot, who chairs Saint-Hyacinthe's waste management committee,could not confirm whether the provincial authorities were briefed on the dump.

Normally, that wouldbe the case for such a move, he said.

Cot says the city takes full responsibility for any mistakes made that resulted in the deaths of the fish.

"We're not happy about it," he said. "We're not hiding it."

'A series of bad decisions'

Saint-HyacintheMayor Claude Corbeilsaid Tuesday that poorcommunicationbetween municipaldepartments led to the dump.

Corbeil said his administration takes full responsibilityfor aseries of errors that led to the dump being approved despite low water levels in the river and its slow flow.

"There was a lack of communication, a series of bad decisions,"Corbeilsaid.

"I can tell you I'm very disappointed and troubled by what happened, which clearly goes contrary to our environmental values."

Corbeil also said he was "greatly troubled"that residents ofSaint-Hyacinthewere not given advanced notice of the sewage release, whichhad been planned as far back as late April.

Drinking water quality was never at risk from the wastewater dump, the mayor said,noting the source of the city's drinking water is upstream from the wastewater plant where the dump originated.

Water levels 'not considered'

Cot said the city's original plan for the sewage release was based on projectedwater levels in the Yamaska River.

"At that time, we were counting on a regular flow of water in the river. But the drought we're being subjected to led the river to be very low for this time of year," he said.

"Employees did not consider that low level when the flush was ready to happen."

The long weekend meant some managers were hard to reach and contributed to the situation, he added.

Corbeilsaid he has asked for an internal inquiry to determine why the sewage dump proceeded despite the unfavourable river conditions.

"This can't happen again," he said.

Sewage may haveled to drop in oxygen

Sarah Dorner, anassociate professor of civil, geological and mining engineeringatMontreal's cole Polytechnique, said the sewage dump likely led to a decrease in oxygen and an increase in the amount of ammoniain the riverwhich combined to kill the fish.

"These are probably the main explanations for what happened," saidDorner,theCanada Research Chair in source water protection.

While the worst is likely over, Dorner said the dump representsyet another stress on a river that already struggles with more than its share of them.

"The Yamaskahas a lot of nutrient pollution from agricultural development. This river also receives raw sewage spills on a regular basis," she said.

The Rivers Foundation, a Quebec non-profit organization dedicated to protecting the province's rivers, said there were651 sewage spills in the Yamaska River in 2015.

In 2015, the City of Montreal faced intense criticism for its decision to dump more than eight billion litres of sewage in the St. Lawrence River.

• World watching as Montreal sewage gets dumped into St. Lawrence River
• Montreal sewage waste dumped directly into rivers