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Mexico City’s rivers reborn

Mexico City has always had an uneasy relationship with its water resources. Once the pre-Hispanic floating metropolis of Tenochtitlán, the city grew against all odds by draining its surrounding lakes and burying its rivers. But now, a grassroots initiative wants to open up the city’s waterways and turn them into parks – bringing Mexico’s rivers back to life.




In Mexico City, the name Viaducto Río de la Piedad conjures images of a noisy, polluted, traffic-ridden six-lane highway that turns into hell-on-wheels, with cars inching by at a mere six kilometres per hour during rush hour. It’s not a place to go for an afternoon stroll, let alone hang around.

Yet in 2012, that’s precisely what a group of activists led by environmentalist architect Elias Cattan did. After scaling a fence on a bridge, they sat down in a circle on the concrete structure that cuts through the middle of the avenue and had lunch. When asked what they were doing, they replied: “We’re having a picnic by the river.”

The initiative was meant to draw attention to what was inside the concrete structure: the Piedad River. In 1942, this waterway became the first urban river in Latin America to be encased in a pipe. Ten years later, an avenue designed to connect to the newly inaugurated airport was built over it and, since then, the only reference to the river has been the name of the highway – río meaning ‘river’ in Spanish.

Those present at the picnic that day wanted to raise awareness about a more significant issue: “We need to relate to water in a more systemic and profound manner”, the group’s manifesto at the time stated, “and stop considering it merely as a consumption resource and more as a force that transforms and gives life.”

The city’s historic battle against water
Initially called Anahuac by the Aztecs – meaning ‘close or next to water’ – the Mexico City valley boasted 45 rivers running down from the mountains into various bodies of water, creating a vibrant ecosystem of marshes and wetlands. The entire city of Tenochtitlán, now Mexico City, was built on top of a lake that was later drained by the Spanish conquistadors to make way for the colonial city.

In the twentieth century, and under pressure from a rapidly expanding city, pollution and waterborne diseases like polio, urbanists followed this anti-hydric tradition by burying many of the valley’s waterways underground. The end result was an increase in floods during the rainy season (Mexico City receives more annual rainfall than London), when the streets become rivers due to a lack of ground porosity – as if nature were fighting back.

The irony is that today, this once water-rich valley – now home to 22 million people – is one of 11 megacities around the world running out of water. The resource needs to be pumped up from lower basins – Mexico City is located 2300 metres above sea level –through the Cutzamala System, a costly infrastructure running hundreds of kilometres.

In this sense, ‘Picnic by the river’ had a particular message: the basin is still alive, and Elias Cattan and his partners had a vision of what the rivers could become.

The birth of the Ecoducto project
Before he began organising the picnics, Cattan had spent over three years working with a team of biologists and urbanists under the men-torship of the Regenesis Group – a US-based thought leader in ecological design. Inspired by cases like Cheonggyecheon Park – an urban renewal project in downtown Seoul that transformed a stream once covered by transportation infrastructure into recreational space – Cattan’s group proposed a project to clean the river, open it up and turn it into a public space.

Cattan’s early version of what would later become the Ecoducto won the prestigious Holcim Award for Sustainable Construction for Latin America in 2011, which drew attention from specialists and environmental activists who then also started doing the picnics. But to a larger crowd, the idea seemed quixotic, at best.

Still, they continued organising picnics year-round. Eventually, their intervention was replicated nationwide by activists like Antonieta Peregrina, who teamed up with local NGOs and activists to stage her own picnics at the polluted Atoyac River, near the city of Puebla.

In 2017, things took a dramatic turn. Environmental activists, including Antonieta Peregrina, civic groups such as Isla Urbana and small businesses, including local restaurants and cinemas, joined forces to create Cuatro al Cubo (Four Cubed), an urban intervention association designed to revitalise the city’s public spaces in a sustainable manner. With this extended quorum, the picnics attracted massive crowds, and Miguel Angel Mancera, the mayor at the time, mobilised the police to expel the activists. Armed with mobile phones, the activists posted the images and videos on social media, catapulting the #picnicenelrio hashtag into a trending topic nationwide.

The tide had turned in favour of the activists, and caving under public pressure, the city’s Urban Development Agency finally agreed to build the park. “At first, they wanted to light up the park with lines of blue lightbulbs to show that a river runs beneath it,” Cattan told me during an interview. “We said that’s fine, but why don’t you actually show them the water, instead?”

As momentum for the Ecoducto project grew, Cuatro al Cubo reached out to Dr Alejandro Federico Alva Martínez, a hydrobiologist at the Universidad Autónoma Metropolitana (UAM) of Mexico and a specialist in designing biofilters for polluted water. He created a small, energy-efficient water treatment plant in the middle of the highway, the only one of its kind in Mexico, which primarily relies on gravity to filter 30 000 litres of heavily polluted river water per day.

The 1.6-kilometre park opened in 2018, and although it uses just a small fraction of the river’s water, it’s already having an impact: “We used to have four species of birds here,” says Alva. “Now we have 17 species interacting with 13 types of water plants and 47 species of insects.”

The new park’s foliage has reduced the traffic noise levels by ten decibels and, according to sustainable impact specialist, Maria Marquez, the project will recoup its cost within the first year. It gives back to the city MXN 80 million (about USD 4 million) a year in the form of ecological services such as water filtering, CO2 capture, smog reduction and ambient temperature regulation, and social services such as public spaces, greenery and playgrounds. And the group’s work is far from over: Peregrina, who now runs Cuatro al Cubo, is in charge of turning the place into a laboratory to educate people about the natural conditions of Anahuac. She has recently inaugurated a Water Pavilion located at the intersection of two streets and the park, where workshops on water treatment, urban farming and social activism will take place.

The park is a long walkway dotted with benches, infographics and small gardens. It’s divided into four parts – the first is the water treatment plant, from where the water flows down to a thematic section on the valley’s wildlife and fauna, continues towards an urban farming plot and ends up at a recreational centre with playgrounds and exercise machines. According to Marquez, the neighbours were initially hesitant to use the park for fear of pollution from the cars, but now it has become an iconic space. In the morning, one can see neighbours jogging, walking their dogs and riding their bikes on their way to work – and the value of the properties near the Ecoducto has increased.

One busy Tuesday afternoon, we meet with Cattan at the park – in the distance, one can see the small stream making its way through gardens and plants. A tourist couple stroll along, a man dressed in a suit sits on a bench talking on the phone, and a young kid skateboards on the walkway. “If it were up to me”, Cattan tells me, overlooking the stretch, “we would open the whole river and have this replicated all over the city. But first, we need to change the relationship of chilangos (Mexico City dwellers) with their environment. This is a good start.”

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Video production: Scott McNamara / Andreas Thomann