Context:

• A huge plume of smoke was spotted emanating from the middle of Varthur lake, raising the spectre of severe pollution leading to seemingly spontaneous combustion.

Details

• While Bellandur lake upstream has had multiple fires caused by chemicals and trapped hydrocarbons in its severely- polluted water, this is perhaps the first time a fire has been reported in the 450- acre Varthur lake.
• On Sunday, residents observed a large plume of smoke within the lake. The fire started around 2.30 p.m. in the centre of the lake where a thick layer of weed covers the surface.
• “The fire broke out about 200 feet from its boundary in Thubarahalli. While there is garbage burning close by, in this case, the spot is not accessible. Around 6 p.m., the smoke died out slowly naturally,” says a resident of an apartment adjacent to the lake.
• Jagadish Reddy from Varthur Rising believes the same phenomenon that caused fires in Bellandur lake in the past could have caused Sunday’s blaze in Varthur. “Even fire officials could not douse the blaze. They were just not prepared for it. Over 20 acres has been charred causing immense damage to the eco-system,” he says.

Difficulty reaching the spot:

• Fire officials sent three fire tenders from Whitefield, Mahadevapura and Sarjapur. “The fire spot was not accessible. We had to wait for a boat to arrive from Mahadevapura. But, by then, the fire started to fizzle out naturally,” said an official.
• While the official said it was too early to ascertain the cause of the fire, the inaccessibility of the location casts a doubt whether it could be intentional or accidental.
• “If we can’t reach it, I’m not sure how anyone else could… Chemicals in the lake could have caught fire due to the heat,” said the official.
• In February 2017, a fire was reported in Bellandur lake. Trapped gases and chemicals in the lake were believed to have caused the blaze, which led to the National Green Tribunal taking up a suo motu case.
• Bellandur lake receives over 480 million litres of raw sewage from the city daily, and much of this flow into Varthur lake.

Why the lake catches fire?

• According to an IISc study, “Discharge of untreated effluents (rich in hydrocarbons) with accidental fire (like throwing cigarettes, beedi) has led to the fire in the lake.”
• It added that the “Incidence of foam catching fire are due to compounds with high flammability, i.e., mostly higher hydrocarbons and organic polymers from nearby industries…
• High wind coupled with high intensity of rainfall leads to upwelling of sediments with the churning of water as it travels from higher elevation to lower elevation forming froth due to phosphorous,” as per the report.