The Bellandur lake in Bengaluru caught fire once again on Thursday evening because of illegal debris dumping in and around the water body. This is the third such reported incident from the lake, parts of which were ablaze for almost three hours before firefighters brought the situation under control, The Hindu reported.

Fire officials said the blaze probably originated from a thick layer of hyacinth inside the lake. However, they were not able to determine what caused the hyacinth to catch fire. “Waste has been dumped in the lake deliberately. Either someone has set it on fire, or the chemicals inside the lake may have got ignited,” an official said. “How can we put out a fire in water?” another asked.

Nearby residents said the constant dumping of waste in the vicinity was the reason for the fire. Indian Institute of Science Professor TV Ramachandra, a member of the state government-appointed committee for lakes, said the fire was likely because of the cumulative effect of a chemical reaction between the hyacinth and a methane layer beneath the aquatic plants.

Ramachandra said the incident was proof of the fact that the Bruhat Bengaluru Mahanagara Palike and the Bangalore Water Supply and Sewerage Board were failing to prevent waste and sewage from entering the lake. Meanwhile, Karnataka State Pollution Control Board Chairman Lakshman said the body was inspecting sewage treatment plants in the area.

Residents around the Bellandur lake and other water bodies have repeatedly complained of foul smells and pollution as these water bodies start frothing because of fires. The toxic froth – produced as a result of allowing untreated sewage water to flow into the lakes – usually spills over onto the roads and into drains in surrounding areas.