Infamous drug lord Pablo Escobar has left the small Columbian town of Doradal with a heavyweight nuisance - hippos straying onto streets and the local soccer pitch.
An estimated 80 hippopotamuses, perhaps more, live in the area around the Rio Magdalena, Colombia's principal river.
They're descendants of four hippos that were brought to the country by Escobar for his personal collection.
The rapid growth of their numbers has authorities worried that residents could be attacked - the three-tonne animals can be aggressive and kill more people per year in Africa than any other wildlife species.
Scientists also worry that their presence threatens the area's native flora and fauna.
During the height of his power in the 1980s, Escobar kept the hippos at a private zoo on his 2225-hectare estate, Hacienda Napoles.
Following Escobar's death in 1993 most of the animals were taken to new homes or died. But not the hippos. Their size and cost to transport meant they were abandoned.
But the animals thrived in the area's large lakes and waterways, and grass pastures, and have brought a tourism boost.
However the animals are having an impact on the native flora and fauna with indications the presence of the animals is displacing some local species.
A new study by researchers at the University of California, San Diego, found the hippos are changing the quality of the water. The hippos feed at night then spend the day cooling off in the water where they defecate, changing the chemistry in the lakes.
"That can have various negative consequences, from the outbreaks of harmful algae blooms and things like red tide bacteria," said Jonathan Shurin, a UCSD biologist who led the study.
"If their population keeps growing the way it is, the potential impact could be much more severe."
That has left local authorities scrambling to come up with a solution to the hippopotamus problem.
Cornare, the environmental agency for the region, has been tasked with finding a solution that residents are comfortable with but deals with the animals in a humane way.
"It's urgent," said Gina Serna, a specialist with Cornare.
"We already have a report of a family of hippopotamuses in the Magdalena river. The Magdalena connects almost all of Colombia so they could move into any part of the country."
Now a plan has been hatched to sterilise the animals. Serna and a group from Cornare last year conducted an in-the-wild surgical sterilisation of a female, the first ever in Colombia.
It's a complex procedure that requires luring and trapping a hippo in a corral before using sedatives to put it to sleep. Just cutting through a hippo's dense layers of skin, fat and muscle takes three hours. Then the animal is sterilised and stitched up and allowed to return to the wild while their recovery is monitored.
Later this year, Cornare will attempt multiple surgical sterilisations, as well as a chemical sterilisation technique that has been successful in pigs.
But they acknowledge that won't be enough to contain a hippopotamus population that is estimated to quadruple over the next 10 years and could eventually reach into the thousands. For now, it's as much as they can afford.
"With more help and more money, we could be more effective," said Serna.
Australian Associated Press