The city's wastewater treatment plant has exceeded its capacity for the second time this month, and released wastewater into Hamilton waterways for over 12 hours.

In a media release, the city says that the Woodward Wastewater Treatment Plant entered "bypass mode" at around 10:36 a.m on Saturday because the extreme wet weather and melting snow exceeded the treatment plant's capacity.

The plant can hold around 409 million litres of wastewater and can accommodate up to 600 million litres — but just for a short amount of time.

The bypass ended that same day at around 11:35 p.m. The release does not indicate how much wastewater was released during this time.

This is the city's second notification of a bypass at the treatment plant since it pledged to post an announcement each time one happens.

The protocol was mandated after a gate was left partially open at one of the city's combined sewage overflow tanks. This allowed 24 billion litres of untreated storm water runoff and sewage to flow into Chedoke Creek over four years.

While city council knew about the leak, it did not disclose its magnitude to the public — it has since apologized and released documents on the incident.

It also approved an "enhanced public notification protocol" for more transparency.

The first notification of a bypass occurred earlier in December — the treatment plant reached capacity during a major winter storm and released 78 million litres of partially treated wastewater over 12 hours into Hamilton Harbour.

Notifications for the treatment plant and 14 of the city's combined sewer overflow tanks are posted on the city's website within 24 hours. A new, more interactive system will come out in the second quarter of 2020.