Is There Still Hope for Latin America's Most Toxic River?

Fifteen years after the Supreme Court ruled the government must clean the polluted basin, Argentina was finally hitting its stride. A new administration may change that. 

A foul liquid gushing from a storm drain bubbles and foams several meters below as it cracks the film on the surface of the river. The color resembles sewage more closely than it does water.

 So does the smell.

“That should be rainwater, but it’s not actually rainwater because people used to illegally intervene and connect their sewer to the storm drains,” cultural guide Lucia de los Rios said through an interpreter. She gripped the railing of the government-operated educational tour boat as it hopped over a swell. In the boat’s wake: plastic bottles and bags, styrofoam, and ripped pieces of construction site tarp. All were swirling together in the odorous, gray-brown liquid flowing through the river channel. 

Very few locals call it water. 

This is Riachuelo de la Matanza in Buenos Aires, the capital city of Argentina. Its translation, literally, is “slaughter creek,” and it has an infamous reputation for being among the world’s most polluted rivers.

For over a century, the Matanza-Riachuelo river basin served as a dumping ground for residents of Buenos Aires, which now has a metro population of more than 15 million. Factories disposed of waste along the shores. Slaughterhouses dumped animal excrement and blood into the water. Sewers, household waste, old cars and ships—virtually anything fit for a dump went into the river.

The result is an environmental and health crisis spanning generations.

In 2004, residents of the “cuenca,” or river basin, filed a lawsuit against the city, provincial, and national governments and industrial polluters along the river and demanded action. The Argentine Supreme Court’s 2008 ruling ordered the government, via the Autoridad de Cuenca Matanza Riacheulo (ACUMAR), to improve quality of life, recompose the environment, and prevent further damage.

Since then, ACUMAR has worked to meet these goals through neighborhood relocation, mobile toxicology, and environmental health units, building new community spaces and removing tens of tons of garbage and debris from the river.

Libertarian-aligned Javier Milei took the reins of the Argentine government in December 2023 following a heated runoff election. His goal, amid Argentina’s devastating financial outlook and sinking peso, is to cut as much spending and as many programs as possible. 

With now 15 years of work sunk into the ACUMAR project with little to show, and the arrival of Milei’s government looking to cut programs, one looming question remains for Argentina’s environmentalists and basin residents: Can all the damage actually be undone?

For many, that answer is no.

The official solution

Antolin Magallanes was the general director of political and social management at ACUMAR during President Alberto Fernandez’s administration. Magallanes has been in and out of the agency several times, as Argentina’s executive branch has authority to appoint civil servants of its choosing into leadership.

But ACUMAR isn’t just another political arm for whichever party controls the Argentine government house Casa Rosada—it’s a different type of agency altogether. 

“It’s a different status for a state office or ministry,” Magallanes explained through an interpreter. “It’s an agency created from a court decision.”

ACUMAR operates under judicial oversight, which not only speeds up the bureaucratic process but also strictly mandates effectiveness.

“I have to elevate a report for each three months to the justice about what ACUMAR is doing,” Magallanes said. “In the cases where [ACUMAR] is not reaching something, above [the agency] is the justice, and sometimes the judge can go farther than [ACUMAR] can.”

But even with its special status, the agency has faced setbacks.

Magallanes said 50% of ACUMAR’s funding should come from the national budget, 25% through the province of Buenos Aires budget, and 25% through the Autonomous City of Buenos Aires budget. He said that's not happening. 

“Neither Buenos Aires province nor city pay what they should be paying,” Magallanes said. “The biggest part of the ACUMAR budget is paid by the national state and therefore funded by every province in Argentina. Some provinces in far areas may pay more than Buenos Aires province or city.” 

That national funding is now at risk.

The new president

Argentina’s newly-elected president promised his electorate he’d eliminate anything he views as non-essential spending. While Milei—whose views on climate and environmental issues are laissez-faire—hasn’t named ACUMAR directly, many of his proposed cuts are environmental-focused. 

Ana Lamas is slated to be Argentina’s new undersecretary of the environment. She’s worked as a legal adviser to ACUMAR, served as undersecretary adviser for the City of Buenos Aires’ environmental ministry 2007-2009, and was institutional director of the National Secretariat of the Environment from 1992 until 1994. 

While she doesn’t directly oversee ACUMAR—the program has a special status—she is calling for cuts and says the agency has grown outside its scope. 

“They have 2,000 people working at the authority (ACUMAR),” Lamas said. “Can you believe that?”

She rebutted Magallanes’ assertion that ACUMAR isn’t getting the resources it needs and torched the agency’s practices. 

“They have to pay 2,000 people, and they have very good salaries,” she said. “I don’t think they had too much trouble getting money. Maybe they didn’t use it correctly.”

ACUMAR’s goal, she said, was to clean the river, but the river is still dirty as ACUMAR pursues other projects, including health testing, housing relocation, and shoreline restoration. 

“I don’t think that has to be done by a basin authority,” Lamas said about some of the programs. 

During his presidential campaign in August, Milei asked the audience at an economics lecture, “What’s wrong with a company polluting a river? … Where’s the problem there? That, in fact, speaks of a society that has plenty of water. The problem actually lies in the fact that there are no property rights over water; when water is lacking, someone will see a business there and will claim property rights. They are going to see how the pollution ends there.”

If that was prior governments’ strategy for the Riachuelo, it has utterly and completely failed. 

“I think that maybe he doesn’t know what ACUMAR is,” Lamas said about Milei’s comment. “But he wants the people who use the resource to take care of it; that’s his policy.”

She continued: “If you say ACUMAR has had good results, I can tell you no. It’s not good to say individuals or organizations have to take care of the river if they want it clean … Maybe it’s exaggerating, but you cannot believe also that the government is going to take care of everything.”

Lamas said there is a role the government must play in the cleanup; re-routing sewage systems that pour directly into the basin, for example. 

“The strength [ACUMAR] had when they were created, now they don’t have,” Lamas said. “They are less effective. Some time ago, when you say ‘ACUMAR is here and they’re going to make an inspection,’ [it was taken seriously]. Nowadays it’s not like that.”

Pushing for change

For Pio Torroja, a researcher and activist with the organization M7RED, the 2008 Supreme Court ruling was a step in the right direction. But he knew the fight wasn’t over. 

“In the beginning, ACUMAR was very suspicious about everything,” Torroja said. “It was a very closed organization in the beginning … we were having a conversation with them but also kind of a fight.”

That fight was for public information.

According to the ruling, the people of the cuenca were to be represented via a civil organization led by an ombudsman, or public servants, and have rights to see ACUMAR information and have meetings with the agency. 

“We tried to push pressure because the Supreme Court asked ACUMAR to have a public information system online and they were trying to avoid that issue,” Torroja said. 

He explained the M7RED team built its own information mapping platform, “Qué pasa Riachuelo,” to show ACUMAR complex mapping of the basin could be done. 

Now, ACUMAR is working on its own epidemiological map to help the agency’s toxicology network and clinics understand what areas need to be better served or relocated. 

Biologist and environmentalist Raul Montenegro said ACUMAR’s “superficial” changes like shoreline parks and public spaces are distracting from a larger, ecological crisis. He criticized ACUMAR for “managing a water landscape” rather than focusing on biodiversity and limnology in the river.

“If you don’t have in mind the ecological profile, maybe you can obtain at the end of the day a more beautiful landscape,” Montenegro said. “But without addressing biodiversity, nothing is ecologically sustainable. … ACUMAR is an interesting experiment, but it’s an initiative that doesn’t cover the entire complexity of the system.”

Buenos Aires was built on a wetland, but the city’s population growth in the 19th century led to most of the city’s streams being entombed underground, leaving Riachuelo de la Matanza as one of the last open-air basins. Montenegro’s view is that the scope of ACUMAR is too small—it can’t change a part of the river without taking into account all of the water that flows into it.

Torroja said since their past quarrels, ACUMAR has improved transparency while simultaneously improving the environment and quality of life in the cuenca.

“We have a better situation now,” Torroja said. “The situation is not good, but it's really better than the old times.”

Life along a toxic river

Villa 21-24 is an area of informal housing on a small peninsula in southern Buenos Aires. In the streets of the dense neighborhoods, vendors sell a baked cheese bread called “chipas” as stray dogs sneak around their feet for crumbs. At the southern edge of town, there’s a football field and a boxing club where younger residents gather. There used to be a garden next to the river, but ACUMAR discovered the soil there was too contaminated to produce safe food, so now it’s just dirt and litter.

For Victor Cornejo, the river is just another part of life in Villa 21-24. 

Hoisting himself up into a wooden enclosure built just off the riverbank, Cornejo reached for an oar hanging from the roof. Smiling, he turned it around to show off the design: two red stripes along with a “21” and “24” to represent the neighborhood. 

“We have the boats locked up due to crime in the area,” Cornejo said through an interpreter. “Boats and supplies were getting stolen.”

Despite the condition of the river, Cornejo and many of his neighbors are in a rowing club, and they’re encouraged by the improvements ACUMAR is making. 

“It’s better,” he said of the conditions. “Before, there were noticeable trash islands floating by.”

Lorena Lencina, who belongs to the club along with her two daughters, agreed.

“[Several] years before, you’d see oil on top of the water passing by,” she said through an interpreter. “Now you can see the water is just water.”

Apart from rowing, the river has no use. Lencina and Cornejo said that prior to the neighborhood being hooked up with water about two years ago, residents hauled water from other parts of Buenos Aires.

Veronica Elibre is the neighborhood’s representative serving on the Institute of Housing of the City (IVC), and she’s not satisfied with ACUMAR’s work in her community. 

“On paper we’re a priority,” Elibre said through an interpreter. “But the transformations we expect are not taking place.”

Elibre said officials are supposed to take care of the housing and “minimum conditions of the houses that are here,” but the neighborhood is being ignored. 

Some neighborhoods in Villa 21-24 have been relocated. The new housing, built alongside the informal settlements, is striking in difference. The apartment buildings are tall, modern, and uniform—much different from the thin, boxy homes built with mismatched materials.

Elibre’s neighborhood has not been updated.

“When they come here to survey what should be done, they are reporting what should be done to improve conditions,” she said. “They have a report that says where infrastructure improvement needs to be, where cleanup needs to be, where structural improvement needs to be.” 

During a survey ACUMAR conducted the day before, Elibre said, the agency documented just half of the things they should have documented about the conditions. She suggested corruption may be the reason her neighborhood isn’t getting the assistance it needs. 

“Funds are going missing and taken somewhere else,” Elibre said. “There are a lot of kids with lead in their blood. A lot of babies and kids are hospitalized with pneumonia because of the level of moisture in the air.” 

During a flood, Lencina and Cornejo explained, the river rose into their homes. They dried everything but started to develop health problems, including eczema and asthma.

According to Torroja’s organization, this isn’t uncommon. While ACUMAR is making substantial progress cleaning garbage and capping sources of new pollution, the heavy metals beneath the surface pose a larger threat and aren't as easy to remove.

“Basin residents are more likely to experience poor health when they are closer to the river,” an M7RED essay reads. “The diseases observed are cardiovascular and dermal diseases, tumors and diarrhea … associated with breathing nauseating odors (and) contact and consumption of contaminated water that contains heavy metals and nitrates.”

ACUMAR’s second quarterly report of 2023 shows the agency visited nearly 15,000 homes and conducted health evaluations for over 6,700 of them.

The report also reveals “lead values above the reference values” in 292 people. Eighty-seven of them were children under 6 years old. 

“The problems haven’t been resolved,” Elibre said. “The government of Buenos Aires is not taking care of this as they should be.”

Changing a culture around the river

“I remember it from when I was a child,” Magallanes said as he flipped through pictures of an older Riachuelo de la Matanza crowded with rusty ships and a shoreline littered with industrial garbage. 

“It’s what happens in every big city where industrial operation is related to the river,” he said. “After a certain time, there’s a breaking point.”

Magallanes said for Buenos Aires, that breaking point came in the 1990s. 

“It’s a very floodable region,” he explained. “[There were] a lot of deposits and warehouses where different kinds of materials were kept illegally. It was a lack of official [oversight], especially in … territory with petrol industries. There was no control at all and corporations handled it by themselves however they wanted.”

During floods, any substances stored in the warehouses—lead, chrome, cadmium, acids, gas, animal effluence—would dilute into the river. 

To make matters worse, an economic downturn bankrupted many warehouses along the river. Former workers and their families settled at these sites and built new, informal settlements, called “villas.”

The abandoned ships, already causing problems by slowing the river’s flow, sometimes became garbage-storage tanks for the new residents of the cuenca.

“The hardest part (of ACUMAR’s mission) was to change the culture about what you do with the river,” Magallanes said. “It was the historic use … of this place just to fill with trash and to do whatever you want.”

Another challenge was finding solutions that work for the people who rely on those historically polluting industries. 

“Ten years ago, (the government) had to … close down (leather tanneries) because of the contamination it was producing,” Magallanes said. “But the people that came here to ask for it to reopen was not the factory but the workers.” 

Today, workers’ unions have commissions for each industry that work with ACUMAR to comply with environmental regulations. ACUMAR presents sustainability plans, and the companies must meet the requirements or face closure. 

As a result, there isn’t much new industrial pollution going into the river, but according to ACUMAR, industrial pollution is less than a third of the problem — 70% of the pollution is sewage.  

“There remains a big part of the southern part of the city that is not connected to the big sewer system,” Magallanes said. "A big water treatment plant is being finished right now that will connect virtually every sewer into the system and end the riverside effluence."

The abandoned ships, already causing problems by slowing the river’s flow, sometimes became garbage-storage tanks for the new residents of the cuenca.

Today, workers’ unions have commissions for each industry that works with ACUMAR to comply with environmental regulations. ACUMAR presents sustainability plans, and the companies must meet the requirements or face closure. 

As a result, there isn’t much new industrial pollution going into the river, but according to ACUMAR, industrial pollution is less than a third of the problem—70% of the pollution is sewage.  

“There remains a big part of the southern part of the city that is not connected to the big sewer system,” Magallanes said. "A big water treatment plant is being finished right now that will connect virtually every sewer into the system and end the riverside effluence."

But the effects won’t happen immediately—or anytime soon. ACUMAR expects it to take years for the slow-moving river to empty the sewage into the Rio de la Plata, the river mouth leading to the Atlantic Ocean. 

“It will not get worse, but it will not be solved overnight,” Magallanes said.

He added that the final shoreline cattle stockyard had moved away from the cuenca and that another in-progress ACUMAR project, an industrial liquid effluent treatment plan, will reduce pollution from the basin’s tanneries that currently rely on the river. 

What now?

Despite the complexities ACUMAR faces, Magallanes is proud of what the agency has accomplished. 

A short walk along the riverbank reveals the work happening in the cuenca: catamarans and excavators, garbage-sifting nets and fenced-in bases of operation line the river.

“It was after the work of ACUMAR that the struggle was recognized as basin scale,” Magallanes said of ACUMAR’s biggest accomplishment. “[It was understood] as a complexity, not as multiple problems.” 

While critics target ACUMAR's scope, methods, and effectiveness, the overall benefit to the cuenca seems universally recognized. Just as it seemed Argentina was finally getting a hold on that complexity, Milei’s administration may now put the basin’s future at risk.

"Because the problem is so huge, it's very easy to say that [it's not working]," Torroja said. "When you have a basin with 6 million people living there in bad conditions … it’s not easy to solve."

And based on Lamas’ and Milei’s words, there may be nothing left to solve.