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Last summer, the world’s attention turned to the famed Seine River to watch as a parade of ferries, tourist boats and yachts carried Olympic athletes through the heart of Paris for the opening ceremony of the Summer Games.
The pageantry of the floating, four-hour saga was punctuated by persistent rain that drenched athletes and spectators alike as the parade cruised past landmarks like the Notre-Dame cathedral and the Eiffel Tower.
Then, at the sound of the starter pistol a few days later, triathletes dove into the water — right at the foot of the Champs-Élysées — for the first leg of their event, a 1.5-kilometre swim.
Years, months — even days — before the starting gun, it didn’t seem possible for the Seine to play such a starring role in the world’s biggest sporting spectacle. For one thing, it was the first time an urban river had been used for an Olympic swim since 1896. For another, swimming had been banned in the Seine since 1923.
That’s because Paris, like Winnipeg, has historically used its in-city waterway as the backstop for its sewage system. Like Winnipeg, the French capital designed its underground maze of sewers to overflow into the river on rainy days, when the pipes that carry runoff and wastewater to the sewage treatment plants are over capacity.
In Winnipeg, these overflows dump, on average, 10 billion litres of effluent into the rivers each year — enough to fill 4,000 Olympic pools.
And like Winnipeg’s Red, Assiniboine and Seine rivers (yes, there’s a Seine in Winnipeg too), those overflows left the Parisian river polluted with E. coli, excess nutrients, garbage and other unsafe and unsightly contaminants — right up until the gun sounded.
The opening ceremony rainstorms had caused an E. coli spike that delayed the start of the swim, but eventually tests came back clean enough to allow the city’s leaders to celebrate a moment nearly a decade in the making.
“Paris has shown that it is possible to bring even the most polluted rivers back to life,” Dianna Kopansky, head of the freshwater and wetlands unit of the United Nations Environment Programme, said in a release a month after the Games ended. “But if we’re to ward off a looming freshwater crisis, the world is going to need a lot more success stories like this.”
Sewer issues like these afflict more than 1,000 North American communities. Many have been working toward solutions for decades and their efforts have laid a roadmap Winnipeg’s policy makers and community groups can turn to as the city charts its own path to cleaning up the rivers. From giant cisterns to rain gardens, storage tunnels and parks, cities across Canada — and the rest of the world — have shown there are plenty of options to stop the overflow of sewage into freshwater.
It might not have happened without the Olympics.
As Winnipeg city councillor and former chair of the city’s water and waste committee, Brian Mayes, will tell just about anyone: convincing a municipal council to spend its limited budget on expensive upgrades to largely out-of-sight, out-of-mind sewer infrastructure isn’t easy.
“It gets frustrating,” he said in a late April interview, referring to his decade-plus of efforts to make progress on the city’s overflow problem. “It’s awareness, it’s political will, it’s costly.”
Winnipeg devised a master plan to reduce overflow volumes in 2019, nearly two decades after the provincial Clean Environment Commission urged the city to start taking quick and meaningful measures to protect its rivers. The plan aims to reduce sewer overflows by about half over the next 70 years, and comes with an estimated price tag of more than $1.15 billion (if you don’t count the contingency that doubles the projected cost).
Progress has been slow; the city budgets between $30 – $45 million each year for upgrades and has spent just under $200 million on everything from new sewer construction to improved data-collection technologies over the last decade, but overflow volumes are just six per cent lower than they were in 1992.
For decades, Paris was in much the same situation: the first pitch to clean up the Seine came from Mayor Jacques Chirac in 1988, the same year Manitoba’s Environment Act came into law and negated the long-standing water pollution exemptions that allowed Winnipeg to dump sewage in its rivers unabated. Like Winnipeg, Paris delayed serious work on river cleanup until the 2010s, starting in earnest to clean the Seine in 2016.
Knowing it had eight years to prepare for the 2024 Games, Parisian leaders seized the moment and came up with a US$1.5 billion strategy, dubbed “the swimming plan,” to reduce the frequency and volume of wastewater that overflows into the river from its network of combined sewers.
The star of the swimming plan was a massive underground cistern capable of holding 50 million litres — 20 Olympic swimming pools worth — of runoff.
It’s a simple, if inelegant, solution: combined sewers overflow when heavy rainfalls overwhelm the capacity of the sewage system, so the cistern captures excess runoff and holds onto it until there’s enough room to pipe the wastewater to a treatment plant.
Occasionally — like the day of the opening ceremony — there are still overflows, but they’re less severe, meaning fewer contaminants flow into the river.
In the 1970s, about 60 per cent of city sewage flushed directly into the Seine, choking off most aquatic life. Studies at the time found just three fish species surviving in the sludge. By 2023, that number had jumped to more than 30 species — a remarkable biodiversity rebound.
In 2023, Paris dumped 1.9 billion litres of diluted raw sewage (a mix of stormwater runoff and wastewater from homes, businesses and industry) into the Seine. At the same time Winnipeg, with a population just two-fifths that of Paris, dumped more than 5.3 billion litres into its trio of iconic rivers.
This summer, Paris expects to open at least three locations of the Seine for public swimming. In Winnipeg, most residents will still try to avoid touching the water.
Today, Ottawa is often cited as a Canadian example of a city taking sewer overflows seriously and developing solutions with a bit of urgency. In fact, it’s one of the cities Mayes has looked to for inspiration on his quest to quell the overflows at home.
“I wanted to do the big tunnel like Ottawa,” he said. “Other cities have done that.”
Mayes is referring to the combined sewer storage tunnel, the six-kilomentre long, three-metre wide, $232-million cornerstone of Ottawa’s sewage overflow reduction strategy. It works much like the cistern in Paris: during heavy rains, it collects and stores about 43 million litres (18 Olympic pools) worth of effluent, which can be gradually pumped back to the sewage treatment plant after rains subside. Funding for the infrastructure came from all three levels of government, allowing the tunnel to be completed within four years.
Between 2006 and 2020 — the year the tunnel was operational — Ottawa saw an average of 622 million litres of effluent spill into the river every year. From 2021 to 2024 there has been an annual average of 210 million litres.
But it wasn’t always that way.
In 2001, a group of Ottawans fed up with the city’s practice of allowing excess effluent to run into the Ottawa River went looking for accountability from political leaders. Because the river serves as the boundary between Ottawa and Gatineau, Que., there were several jurisdictional authorities to appeal to, and the residents decided to form their own non-profit entity to co-ordinate their advocacy efforts.
Ottawa Riverkeeper is a member of the international Waterkeeper Alliance — a global network of community advocacy groups with a mandate to hold politicians accountable to protecting local water bodies.
“Without any clear, single entity to hold accountable for these overflows, Ottawa Riverkeeper was formed,” Laura Reinsborough, current Riverkeeper and CEO, said in an interview. “This organization was formed around the issue of combined sewer overflows and responded to the need for an independent entity that could look out for the health of the river.”
The group’s advocacy originated out of a desire to stem the combined sewer overflows that made the river unsafe for recreational activities. Nearly 25 years later, Reinsborough said, “it’s been one of our biggest successes.”
Reinsborough says the Riverkeeper group worked closely with city officials, advocating for publicly available overflow data (including an email notification system and real-time overflow map not unlike Winnipeg’s), they trained community members to conduct water-quality monitoring, and eventually helped the city develop overflow-reduction targets and decide on a solution that would work within the tight constraints of the municipal budget.
“We assumed that the city of Ottawa did not want to be polluting the river and that they wanted to find solutions, and we — as a community group — could be a strong partner with them to bring that to the public and to other levels of government,” Reinsborough said.
But Winnipeg isn’t likely to get its own big tunnel anytime soon.
“Our staff wanted no part of that — too costly, I think,” Mayes explained.
Costs aside, there are logistical complications. A single tunnel works in Ottawa because the city has just over 100 kilometres of combined sewers (compared to just over 1,000 kilometres in Winnipeg) and most are clustered within a relatively small radius. Winnipeg’s overflows stretch from the western extent of the Assiniboine River to the northern city limit on the Red River and south on the smaller, shallower Seine River (not to be confused with the Parisian Seine).
Winnipeg’s ultimate overflow solutions will be doled out on a neighbourhood-by-neighbourhood basis; the 1,300-page master plan includes detailed engineering plans for each of the 43 combined sewer districts.
In some regions, Winnipeg will take the most extreme and expensive approach by building new pipes to completely separate the sanitary sewage (a term for all the gunk flushed down toilets, sink drains, showers and other indoor plumbing) from the stormwater runoff. Sewer separation makes combined sewer overflows moot, and allows all the sanitary sludge to be processed at treatment plants. Sewer separation projects are currently underway in the St. James, Seven Oaks and Fort Garry neighbourhoods.
But it’s not feasible everywhere. As Ontario’s Environmental Commissioner, Gord Miller, wrote in a 2009 report on sewage issues in the Ottawa River: “The construction of sewers requires the destruction of existing infrastructure, especially roads. In older built neighbourhoods, the extent of destruction required may simply be beyond all reasonable limits with respect to the functioning of the city.”
Instead, Winnipeg plans to combat its woes with a combination of sewer separation, in-line storage (building control gates to hold overflows in the combined pipes during light rainfalls and pumping the effluent back to a treatment plant after the rain subsides), offline storage (like cisterns and tunnels) and screens that limit garbage from entering the rivers during an overflow.
All of these concrete, steel and heavy machinery solutions are called “grey infrastructure.” While they are an important — and proven — piece of solving complex problems like combined sewer overflows, they aren’t enough on their own.
According to the most recent Canada Infrastructure Report Card, the state of municipal infrastructure nationwide is at risk. A majority of this infrastructure is more than 20 years old and “concerning amount” — including 10 per cent of sewer infrastructure — is in poor or very poor condition. Many sewer pipes are now more than 50 years old and approaching end of life at a time when climate change threatens to add additional strain.
“We see these big shifts in temperature or big shifts in precipitation, bigger storm events, bigger rainfalls,” Dimple Roy, water management director at the International Institute for Sustainable Development, said in an interview.
“And these shifts in temperatures mean that we’ll see cracks in pipes, and the aging infrastructure will fail us on occasion.”
Replacing this infrastructure often falls on municipalities, which own about half of sewage assets, but the costs are often out of reach for their budgets. To Roy, a city’s best course of action is to invest in “infrastructure refreshes” in critical areas — where the pipes are most at risk of failure, or release the most overflows — and balance those grey infrastructure investments with green, or natural, infrastructure solutions.
“Essentially, we want to see more spongy areas created in the city,” she explained, noting the “sponge city” concept has come into vogue in cities like Vancouver, Montreal and Toronto.
It’s a simple theory: sewer overflows happen when there’s too much runoff entering the storm drains for the pipes to handle, but if a city can limit the amount of water running over concrete and asphalt into the drains, it can take pressure off the pipes and reduce the frequency of overflows.
The easiest way to do that is to encourage nature to take its course. Where urban environments were traditionally designed to wick water off the concrete and into the drains as fast as possible, natural ecosystems tend to absorb and store that same water like a sponge and release it slowly back into the environment.
By swapping out impermeable surfaces like concrete and asphalt for permeable ones — be it parks, green roofs, rain gardens or even more permeable types of pavement — cities can allow nature to share some of the load, and save money in the process.
Vancouver has implemented “tree trenches” on medians that filter rainwater through soil around a roadside tree and collect the excess into a holding tank below, releasing it slowly back into the environment. Toronto mandates all buildings of a certain floor space install green roofs, which reduce noise pollution while capturing up to 60 per cent of the rain that falls on them. Montreal has policies to build “sponge sidewalks” and “sponge parks,” which it expects will retain three Olympic swimming pools worth of water at half the cost of a grey infrastructure equivalent.
Winnipeg’s master plan does account for green infrastructure. Of the total $1.1 billion capital cost estimate, $104.6 million (about 10 per cent) was designated as “green infrastructure allowance,” and each district is required to have a green infrastructure element. But there’s a caveat: the city recommends 10 years of pilot projects and testing to evaluate the sustainability of green infrastructure before committing wholeheartedly.
While Mayes gives the city credit for ensuring green infrastructure will be part of the broader sewage solution package, he’d like to see Winnipeg pick up the pace on implementing it.
“My job is to be the nag to keep saying: ‘How much have you done? What are your plans? Stop doing zero,’ ” he said.
Roy notes some of the newer developments in and around Winnipeg have already proven the case for these spongy solutions. Communities like Sage Creek and Meadowlands have retention ponds with native wetland plants that absorb and filter runoff.
In 2015, Save Our Seine, a community group dedicated to maintaining the wellbeing of Winnipeg’s Seine River, installed a rain garden near a riverside trail and a large grocery store. The garden collects runoff from the roof and parking lot of the grocery store and filters it through a 450-square-metre patch of native plants and trees, cleaning and absorbing runoff before it drains into the Seine. The garden cost about $100,000, and was planted by a group of about 75 volunteers. The city references the garden as an example of green infrastructure in its sewer overflow plan.
“Those are the kinds of solutions that we would propose as much as possible,” Roy said. “There are some opportunities to … think strategically about where we can invest a bit of money and get quick wins.”
Ultimately, a combination of tight budgets and a lack of political will remain the biggest barriers to making progress on reducing sewer overflows.
In Paris, the spotlight of the Olympic Games created the conditions for municipal leaders to invest in sewer system upgrades.
In Ottawa, a mid-2000s sewage scandal — wherein an equipment failure caused more than 764 million litres of raw effluent to pour into the Ottawa River and city officials kept the incident under wraps for two years — created outrage and public awareness of the overflow problem.
But according to Reinsborough, with Ottawa Riverkeeper, it was the two decades of education, collaboration and consultation between citizens and the municipal government that eventually led to success.
“Together, our voices were stronger, their argument became stronger, and I think that helped them find the political will … to ensure that they could find solutions,” she said.
Marianne Cerilli, a former provincial MLA, and a long-time environmental advocate, was inspired by the Ottawa Riverkeeper approach when she tried to organize her Wolseley neighbourhood to raise a stink about sewer overflows to their councillor. It was part of a broader effort — ultimately interrupted by COVID-19 lockdowns — to create a network of well-supported community groups, able to advocate on an almost block-by-block level.
As Winnipeg grapples with its own legacy of sewage spills, she believes neighbourhood-by-neighbourhood organizing will be key to convincing leaders to invest in changes.
“When elected representatives hear from people from their local ward … when they’re being lobbied and there’s research presented to them and policy advocacy from their constituents, then they pay more attention,” Cerilli said in an interview.
“There is power and strength in numbers. That’s the kind of community development that’s needed in our city — on issues like the combined sewers, and many others as well.”
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.
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