A beaver dam is doing what expensive flood works were meant to do in west London.

A colony relocated to Paradise Fields in 2023 appears to have stopped routine flooding near Greenford tube station, according to staff with the Ealing Beaver Project. The beavers were brought from Scotland as part of an effort to rewild parts of the city.

“Everything downstream is much more protected from flooding than it was before, all because they want to hold that water back so that they have enough water to swim in and feel safe,” said Şeniz Mustafa, with the Ealing Beaver Project. “It just has such a brilliant secondary benefit for us.”

A major part of the original pitch for the project was that beavers, as natural engineers, could reduce flooding and let the local council scrap or scale back planned engineering works. Two and a half years later, project staff say Greenford station has not flooded since.

Beavers have not lived in London for about 400 years. They disappeared after being hunted for their fur, meat and musk. A limited number started to be reintroduced to the region in 2009, beginning in Scotland.

London got its first beavers in 2022, when a male and female pair were released into a specially designed enclosure in Enfield, in the north of the city. They were named Justin Beaver and Sigourney Beaver.

A year later, after community groups pushed for another London project, five beavers were released into the 10-hectare wetland at Paradise Fields, less than 10 kilometres from Heathrow Airport.

There are believed to be at least eight beavers at the site, including Willow, who Mustafa said was the heaviest beaver ever translocated in the UK. At the time, Willow weighed 30 kilograms.

“I am sure she weighs a little bit more now but I don’t want to body shame her, but she is a big mum.”

Willow had kits in 2024 and 2025, including two named Chompy and Chewy by staff. She recently gave birth again, but staff do not know how many kits she had.

The fenced Ealing project is part of a wider push to improve London’s natural environment. There are proposals to release more beavers in Croydon, in south London.

In 2021, London Mayor Sadiq Khan launched a rewilding fund that has provided 2.48 million pounds, or $4.5 million, to dozens of projects to create and restore habitat in the capital. In a statement to CBC News, his office said it was “fantastic” to see the Ealing beavers thriving.

“It’s incredible that in only a few short years they have potentially helped stop flooding at a local station, transformed Paradise Fields into a flourishing wetland and helped to improve the biodiversity of the area.”

Mustafa said the beavers are also changing the site in ways that help other species. They create deadwood that gives insects places to live, and those insects become food for other animals. She said there appear to be new fish at the site, along with more birds and insects such as dragonflies.

Mustafa works as an “urban beaver officer,” promoting the idea that beavers and humans can coexist peacefully. The park is open to the public 24 hours a day, and she said some users have told her the beavers have made it feel safer. She said the animals have felled trees, making the canopy less dense and more open, and have also drawn more people to the area.

A few times a week at dusk, Mustafa leads beaver safaris that are often sold out. The tours cost nearly 28 pounds, or more than $50. Visitors are given binoculars, guided through the site and taught about beavers, including that the animals in London are the Eurasian species.

Amanda Ram, 25, joined one of the tours after seeing the David Attenborough documentary Wild London. She watched Willow approach the crowd and stay for about 15 minutes.

“That was the most amazing thing I’ve ever seen,” she said in an interview with CBC News afterward.

Outside the entrance to the project is a large mall of big-box stores, and the tube station is a short walk away.

“I think it’s really cool that there’s a McDonald’s right here and there’s a TK Maxx and then there’s, like, this project which you wouldn’t expect to be in this park,” Ram said.

Beavers are a protected species in the UK, and it is an offence to capture, kill or disturb them. Last year, the UK government changed the law to allow beavers to be released into the wild in England if the government grants a licence after considering nearby infrastructure and farming.

The Wildlife Trusts, a group of wildlife conservation organisations across the UK, hope to release 100 beavers into the wild this year.

“I’m hoping that we’ll inspire other projects,” said Mustafa. “We will prove … that people and beavers can live together in an urban landscape.”

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