The city of Regina is dumping untreated and partially-treated water into Wascana Creek.
Residents are being warned not to use the creek for recreational activities.
The lagoons at the city's sewage treatment plant are at capacity because of heavy rainfall in recent days, so excess wastewater had to be diverted.
The city said the issue only affects wastewater and assures the drinking water is safe.
Wastewater bypassed into creek
On Sunday, the city began temporarily bypassing wastewater at the city's main pump station at McCarthy Boulevard. The wastewater was screened to remove non-organic solids before it was released into Wascana Creek. However, the water was not treated. That release ended today.
Then on Tuesday the city began releasing partially-treated wastewater at the sewage treatment plant. 25 per cent to 40 per cent of the partially-treated water there is constantly flowing into the creek.
This plant is on the west side of Regina, and the sewage will not be flowing through the city.
The water at sewage treatment plant is expected flow into the creek until next week.
Bacteria in wastewater
At a press conference today, the city said most of the water is fully treated, but there are higher levels of bacteria in the water and it is not removing phosphorous.
Residents downstream from the wastewater treatment plant are being advised not to use the creek for recreational activities because of bacteria in the water.
The city is still waiting on test results on the water taken from the creek to determine its level of contamination.
There was concern the untreated water would affect lakes in the Qu'Appelle basin, but Saskatchewan's Water Security Agency said that is not true.
According to the agency, by the time the water flows out of the creek and reaches the Qu'Appelle lakes it will be so diluted that it will no longer be a health issue.
Brent Rostad, acting director of Water Works Services at the City of Regina, said new infrastructure is important to prevent this situation from happening again.
"The new (wastewater) treatment plant will be upgraded. It'll help us in these types of situations. So we are planning and building for the future."
Residents are still being asked to reduce the amount of water they use to limit the amount of wastewater coming back into the system. The city also asks residents to direct any water they pump from their properties to the storm water system through a catch basin.
The city said people can return to regular water usage by the weekend.