The City of Winnipeg has been charged under Manitoba's Environment Act for a sewage plant glitch that led to billions of litres of partially treated sewage flowing into the Red River last fall.

The province says it has laid the charges in connection with the malfunction at the South End Water Pollution Treatment Centre.

The plant released 2.6 billion litres of partially treated sewage into the river for seven weeks starting on Oct. 7, 2011, when one of the facility's four sewage treatment processes stopped working.

"It was about 60 million litres a day, 50 to 60 million litres a day, of partially untreated waste water that entered into the Red River," Dan McInnis, an assistant deputy minister with Manitoba Conservation and Water Stewardship, said Thursday.

"It didn't meet any environmental requirements associated with their Environment Act licence."

The city did not officially report the problem to the province until almost a month later, on Nov. 1.

"It's a very significant environmental situation," McInnis said.

"Manitoba takes environmental protection very seriously, and that's why we did the investigation we did."

Operation of the sewage treatment plant is "regulated through a licence issued by Manitoba Conservation and Water Stewardship under the Environment Act," the province said in a release.

The Environment Act charges that have been laid against the city include:

• Releasing or allowing a pollutant to be released.
• Releasing or allowing a pollutant to be released in an amount, at a level or at a rate of release that exceeds limits provided under the licence.
• Failing to report the release of a pollutant that may cause an adverse effect on the environment.

If the city is convicted, it could face a penalty of up to $500,000.

An outside review of the incident has determined that bacteria required to treat the raw sewage was reduced, resulting in the sewage being only partially treated.

The bacteria was likely reduced due to "low oxygen levels and increased sludge volumes," the province said in the release.

The review gave the city a number of technical recommendations to ensure a similar situation doesn't happen again.

The City of Winnipeg says it has been notified of the charges and officials are currently reviewing them as well as the accompanying engineering report.

However, officials noted that based on an early review of the report, it appears they have "already implemented the majority of the report recommendations," the city said in a release.

The province noted that earlier this year, it ordered the city to replace the South End Water Pollution Control Centre with a new state-of-the-art sewage treatment facility.