Julia-Simone analyzed ten years of data, searched in archives and requested court records to report this story
May 13, 2025 5 min. read
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10 billion litres of sewage are dumped into Winnipeg’s lakes and rivers each year. Some Winnipeggers avoid touching river water altogether — but others say the untreated sewage is not as bad as it sounds.
Winnipeg was built around its iconic Prairie rivers. The Red and Assiniboine weave through the city — wide, flat and muddy brown — and meet at the Forks, right in the centre of town. They are the heart and pulse of the city. And yet, you’d be hard pressed to find anyone swimming, playing or basking or in their waters.
Why? Well the currents are deceptively fast, the banks are steep and muddy and — as everyone will tell you — they’re full of crap. Sewage, to be precise.
From its inception until the 1960s, Winnipeg built infrastructure to back up onto the waterways. Older neighbourhoods are characterized by a subterranean web of “combined sewers,” which collect both storm drain runoff, and “sanitary sewage” — another term for wastewater carried from toilets, sinks, dishwashers, showers and other indoor plumbing fixtures.
This wastewater mixture is usually pumped to a sewage treatment plant, but when it rains hard or the snow melts fast, those combined sewage pipes can be overwhelmed and the excess sewage overflows straight into those iconic rivers.
The Red and Assiniboine rivers weave through Winnipeg. The Narwhal and the Winnipeg Free Press dug into data on how much sewage is released directly into the waterways. Photo: Mike Deal / Winnipeg Free Press
With climate change projected to bring more intense rainstorms, flash floods and temperature swings to Prairie cities like Winnipeg, sewage overflows threaten to become a more frequent affair.
“When the volumes get too big, you either have to dump it into people’s basements — up through their toilets — or the safety valve becomes the river,” Winnipeg city councillor Brian Mayes says in an interview.
“Politically that was a choice made somewhere along the way: we’re going to dump it in the river.”
The Narwhal and the Winnipeg Free Press dug into the data. The result is a sprawling portrait of the river system where sewage is dumped — and the lake it feeds. Here are five key numbers you need to know.
115 billion — the total litres of sewage dumped into Winnipeg’s lakes and rivers
Between 2013 and 2023, the city dumped 115 billion litres of diluted sewage — a mix of storm water and the stuff we flush down our drains and toilets — into its river system, according to an analysis of publicly available sewer monitoring data. That’s enough to fill nearly 46,000 Olympic swimming pools.
1,037 — the length of combined sewage pipes in Winnipeg
Winnipeg has 1,037 kilometres of combined sewer pipes, many large enough to comfortably house an elephant. The pipes can fill an Olympic swimming pool with water — or sewage — every four minutes. Those pipes serve about one-third of the city, mostly in central neighbourhoods built before 1960, when the city started using separate sewers for runoff and wastewater from buildings.
70 — the number of years it could take to get the sewage leaks under control
The city has a plan to reduce (but not eliminate) sewer overflows by 2095 at the latest. The plan is to chip away at upgrades like underground storage, sewer separation and green infrastructure to capture 85 per cent of combined sewer flow (compared to 74 per cent in the baseline year 2013) at an estimated cost of $2 billion (in 2019 dollars).
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The plan would effectively cut overflow volumes in half. With financial support from other levels of government, the work could be done “close to 2045,” the plan says. If the city goes it alone — as it’s done so far — it will take the better part of 70 years, with a target completion date sometime in 2095. “It will take a long time to do it, but it shouldn’t take 70 years,” Mayes says.
“Other cities are dealing with this. I think we should certainly be picking up the pace.”
1,300 — the average number of times sewers overflowed each year
Between 2013 and 2023, Winnipeg’s 76 sewer outfalls overflowed a combined average of 1,300 times per year. Each outfall overflowed an average 15 times per year.
Each spill dumps nearly eight million litres of diluted wastewater — a blend of runoff and sewage — into the river system, for an average total of more than 10 billion litres every year. (And that’s not counting the extra 14 million litres flushed annually as a result of accidents and equipment failure.)
3,000 — the factor by which E. coli in rivers can exceed guidelines during a sewage leak
Water sampling on the Red and Assiniboine rivers shows the concentrations of suspended solids, phosphorus and escherichia coli (E. coli) nearly always exceed provincial standards after a sewer overflow. E. coli levels in particular can rise above three million units per 100 millilitres. The provincial guideline during an overflow is 1,000 per 100 millilitres — meaning E. coli levels can surge to 3,000 times that guideline. The federal guideline for safe swimming is even lower: 235 units per 100 millilitres.
An overflow at a combined sewer outfall in winter 2021 caused outrage as sludge poured out over a popular skating trail. Photo: Mike Deal / Winnipeg Free Press
$5.5 billion — the total compensation demanded by 11 First Nations over Winnipeg sewage issues
After a particularly egregious spill into the Red river in 2024, 11 First Nations downstream of the river and surrounding Lake Winnipeg filed lawsuits worth a combined $5.5 billion against all three levels of government, alleging they have breached Treaty and Charter rights by failing to address Winnipeg’s decades of water pollution. The three suits, originally filed separately, are now being litigated together.
“Treating the Red River and Assiniboine River as part of the sewage system has polluted Lake Winnipeg,” the statement of claim says.
The nations say repeated sewage releases into the river — and the impacts on Lake Winnipeg — have caused health problems, destroyed fisheries, limited access to drinking water, prevented traditional practices and had adverse psychological effects, including a mistrust of the waters.
For its part, the city denies that sewage overflows and spills have damaged the lake or infringed on the First Nations’ rights. In a statement of defence filed in early May, the city said the sewage it releases into the river system has minimal impact on nutrient loading in Lake Winnipeg and is “not responsible for the impacts on the health of Lake Winnipeg.”
“Nutrients and pollutants flowing into Lake Winnipeg come from a variety of sources both inside and outside of Manitoba, including wastewater and surface runoff from large regions of intensive agriculture,” the city said.
Julia-Simone Rutgers is a reporter covering environmental issues in Manitoba. Her position is part of a partnership between The Narwhal and the Winnipeg Free Press.
Another year of keeping a close watch
Here at The Narwhal, we don’t use profit, awards or pageviews to measure success. The thing that matters most is real-world impact — evidence that our reporting influenced citizens to hold power to account and pushed policymakers to do better.
And in 2024, our stories were raised in parliaments across the country and cited by citizens in their petitions and letters to politicians.
In Alberta, our reporting revealed Premier Danielle Smith made false statements about the controversial renewables pause. In Manitoba, we proved that officials failed to formally inspect a leaky pipeline for years. And our investigations on a leaked recording of TC Energy executives were called “the most important Canadian political story of the year.”
Here at The Narwhal, we don’t use profit, awards or pageviews to measure success. The thing that matters most is real-world impact — evidence that our reporting influenced citizens to hold power to account and pushed policymakers to do better.
And in 2024, our stories were raised in parliaments across the country and cited by citizens in their petitions and letters to politicians.
In Alberta, our reporting revealed Premier Danielle Smith made false statements about the controversial renewables pause. In Manitoba, we proved that officials failed to formally inspect a leaky pipeline for years. And our investigations on a leaked recording of TC Energy executives were called “the most important Canadian political story of the year.”
Since the election of Prime Minister Mark Carney in April, Alberta and the federal government have been talking about a “grand bargain” to balance rapid...
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