Toronto flooding: Partially treated wastewater dumped into Lake Ontario, city says [Video]

The city dumped more than 1,300 megalitres of partially treated wastewater into Lake Ontario during Tuesday’s torrential downpour, which is enough to fill 500 Olympic-sized swimming pools.

A city spokesperson said three wastewater plants were “bypassing,” a process in which stormwater and sewage are diverted from a secondary treatment procedure.

IN PHOTOS: A look back at the massive flooding across Toronto

“The bypassed wastewater still goes through screening, grit removal, primary treatment, phosphorous removal and full disinfection to ensure the treated water always meets strict federal and provincial regulations,” the spokesperson said, adding that the process is done to protect the plants’ ability to continue treating wastewater during an extreme rainstorm.

Health officials have advised against swimming in Lake Ontario for 48 hours after rainfall due to the possible presence of high levels of bacteria. On Wednesday, all of Toronto’s beaches were under a red flag.

The 10 beaches were marked unsafe for swimming due to high levels of E.coli in the water.

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