Leuven (Brussels Morning Newspaper) – Blue-green algae discovered in the Leuven-Haacht canal between Leopold I bridge and Tildonk Lock is toxic to humans and animals. 1 man drowned recently, and police warn that swimming is illegal.
As VRT News reported, Blue-green algae, also known as cyanobacteria, have been found in the canal between Leuven and Haacht. They said that this algae could emit toxins that can harm humans and animals. Upon contact, it can irritate the skin, impact the gastrointestinal tract, and result in serious medical conditions if ingested or inhaled.
The authorities also add that during the hot summer months, there are still some individuals swimming in the canal. This is against the law and incredibly unsafe. On Wednesday, Aug 13, 2025, one man drowned when he swam in the canal with his friend. The authorities warn that the ban should not be ignored, as this can result in severe accidents or death.
What makes the Leuven-Haacht canal dangerous as blue-green algae spreads?
According to officials, the canal is a waterway that is navigable with boats crossing frequently, which contributes to the risk for those swimming. In contrast to protected swimming spots like De Plas in Rotselaar, no guards are present to assist in cases of emergency. Police reiterate that it is strictly prohibited to swim in this canal. Authorities call on everyone to avoid getting into the water and adhere to safety.
Blue-green algae have been spotted in the canal between the Leopold I railway bridge in Wilsele and the Tildonk Lock. Officials mentioned that animals, particularly dogs, are at high risk if they drink or swim in the water. The algae usually appear in the summer when the water is warm. They can be recognised by a blue-green, oily layer that forms on the surface of the water.
“Now that blue-green algae has also been discovered in the canal, there’s an additional reason to observe the swimming ban,”
The police say.
The city of Leuven has erected additional signs along the canal to alert the public to the presence of blue-green algae and to remind the public that swimming is prohibited. The officials remind everyone that the rules are designed to protect people and animals and to prevent accidents from occurring. Authorities encourage compliance with the safety guidelines and urge all individuals to remain safe by avoiding the contaminated portions of the canal.
In 2023, authorities warned about toxic blue-green algae in the Brussels Canal after a heatwave. Health officials advised people to avoid the water and stay away from swimming. In 2022, several areas in Flanders also reported algae blooms. Officials closed parts of lakes and ponds and banned swimming to protect the public.
