Calgary,
29
March
2025
Calgary, AB – The City of Calgary has responded to an unintentional wastewater leak into the Bow River. On Friday, crews identified a leak on the east bank of the river, across from the Bonnybrook Wastewater Treatment Plant by the Ogden Road bridge. Within three hours, they were able to identify the pipe that was the source of the leak, shut valves leading to it, and divert wastewater flows to two other pipes in the area.
Upon discovering the leak, we immediately reached out to Alberta Health Services, Alberta Environment and Protected Areas, and communities downstream. Monitoring indicates this action has contained the issue, but we continue to test water quality and assess the situation.
No impact to drinking water, no current advisories
Calgary’s drinking water, which comes from sources upstream from this leak, remains safe to drink.
Alberta Health Services says, based on available data to date, the risk to the public as a result of this event is extremely low.
There are no boil water advisories or recreational use restrictions for the Bow River in place at this time.
Leak discovered after extensive investigation
City crews first noticed a potential issue on March 19, when monitoring systems at the Bonnybrook Plant identified that the wastewater levels flowing to the plant were lower than normal.
They began looking at potential causes for these lower levels to see if they could be explained by normal seasonal variations, issues within our plant or other factors.
As we were doing these investigations, the wastewater levels arriving at the plant continued to drop each day.
When no issues were found within the plant, crews started to look for external factors that could have caused the issue.
This included talking to regional customers to see if they were sending us less material than normal and looking for any indication of a leak on the 5,000-kilometre wastewater system, including changes at any of our lift stations or 311 reports that could indicate a problem, but nothing was found.
On Thursday, March 27, we took water samples for testing and conducted a visual inspection of the river bank near the treatment plant, which did not see any indication of a leak into the river.
On Friday morning, test results on river water showed elevated E. coli levels in the river near the Bonnybrook Plant. As a result, crews conducted another visual inspection of the river at approximately 11 a.m. and saw a visible leak.
There are three pipes in that location that carry untreated wastewater under the river and to the treatment plant. Our crews began investigation to identify which of these pipes was the source of the leak.
By 2:30 p.m. Friday, we had identified which pipe was the issue, closed the valve to that pipe, and rerouted the wastewater to the two other functioning pipes so that service could continue normally.
Since that time, wastewater flows into Bonnybrook Wastewater Treatment Plant have returned close to normal.
Redundant pipes allowed service to continue
“This incident highlights the importance of having built-in system redundancies. Within hours of getting the test results, we shut down the impacted pipe,” says Doug Morgan, General Manager of Operational Services.
“The three wastewater pipes leading to the Bonnybrook plant are designed to support each other in cases like this, ensuring continued service to Calgarians.”
The City is currently conducting a full assessment of the incident.
“We know when it comes to infrastructure, Calgarians want to know about incidents as soon as we know,” said Mayor Jyoti Gondek. “When I learned of this leak last night, I immediately called a briefing and told the team we needed to share all details with the public at our first opportunity. “This incident highlights the importance of strong back-up plans. Because of those plans Calgarians can have confidence in the systems they depend on daily.”
Alberta Health Services, Environment and Protected Areas (EPA) and The City will continue to monitor the situation, including sampling and testing of the drinking water to ensure it remains safe for consumption. Calgarians, and their pets should avoid contact with the affected area. Fish should be cooked before being consumed.
The City has also notified downstream communities, including Heritage Pointe and the Siksika Nation, and is offering support with water quality testing.
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