A river near Zug has been turned white by pollution from a suspicious substance, which experts have now identified as milk. The now-white Sarbach river in the municipality of Neuheim in Switzerland has been the subject of a police investigation ever since an attentive citizen alerted the authorities to the strange-looking water on Wednesday morning. 

No fish have been killed by the incident 

Swiss police believe hundreds of litres of milk were poured into the river at some time during the night between Tuesday and Wednesday, March 8. So far, there is no evidence to suggest that a fish kill has taken place because of the milk.

After a brief investigation, the authorities in Zug wrote in a statement on March 9 that they had traced the cause of the pollution to a local farmer. As it turned out, the milk had made its way into the sewage system at the farm and into the river because the farmer "hadn't been paying attention". It is currently unclear whether any further action will be taken.

River pollution incidents in the spotlight in recent months

A number of high-profile incidents around the world in recent months have sparked discussions about water pollution and how it affects rivers. In August 2022, the Oder river between Germany and Poland experienced a devastating fish die-off, with a political spat breaking out between the two countries over the ecological disaster. In 2021, a milk tanker overturned in Wales and made the headlines for turning the Welsh river Dulais pearly-white. 

Not all instances of milk ending up in a river are accidental, though. In some cultures around the world, milk can be poured into rivers, lakes or other bodies of water as part of an act of worship or a religious offering, but many scientists and ecologists advocate against these practices, as evidence suggests milk propels the growth of bacteria in water.