Once the high flow levels increased beyond normal operating range, there were concerns over equipment failures and power outages.
Winnipeg, Canada, had to release 59.6 million liters of untreated sewage into the Red River during a weekend storm.
According to CBC News, without the release, there would have been a risk of having it back up into basements.
"It's a difficult decision that we have to make," said Chris Carroll, the city's manager of wastewater services, reported CBC News. "On the one hand, it's difficult for this to happen in the community, and that's unfortunate. The other alternative is you have sewage waste water piling up in people's basements. And in this instance, if there was issues at the treatment plant, which is the end of the system, it's possible you'd have quite widespread basement flooding in the south end of the city."
The rain began Apr. 22 and stopped Apr. 24. Up to seven centimeters was dumped in some parts of the city, impacting underpasses and roads.
According to the city's Water and Waste Department's reporting, the high flow levels at the South End Wastewater Treatment Plant exceeded capacity, which is four raw sewage pumps, reported CBC News.
Once the levels increased beyond normal operating range, there were concerns over equipment failures and power outages.
"It was decided that there was a serious risk of basement flooding upstream of the treatment plant and, considering the current and forecasted weather conditions, steps were taken to divert flow…directly to the Red River," according to the city’s Water and Waste Department’s incident report, according to CBC News.
On Apr. 24, the pumps at three wastewater pumping stations were shut down, which diluted wastewater and released it into the Red River, due to overflows. The pumps were turned back on Apr. 25.
Overall, the sewage poured into the water for one day, 22 hours and 55 minutes, according to the report, reported CBC News. The south end treatment plant took on 1.256 billion liters of water, however. According to the report, there have been releases every day from Mar. 15 until the 22nd in 2022.