The alarming pollution level in lakes in the city was brought into focus when the parts of the Bellandur lake at Yemalur exit point in Bengaluru East became a blazing inferno for most part of Friday night.
Resembling burning lava from a volcano, the toxic froth caught fire on Friday night and the froth-filled parts of the lake were seen burning all through the night.
The conflagration, witnessed for the first time at the lake, not only left the people in the vicinity shocked but also scared many passersby.
Angered over the escalation of pollution levels that brought things to such a pass, the citizens from the nearby areas vented their ire against civic and revenue officials for failing to intervene and prevent pollution of the lake.
Speaking to Bangalore Mirror, Vivek Kumar, a resident of Yemalur, said, "Late in the evening, we felt a strange burning sensation and thought it was because of the intense froth covering the lake. But later we saw luminous red patches over the surface of the water. On looking closely we saw a raging fire beneath the froth. In less than an hour, the fire occupied the entire lake where there was frothing."
Experts who were surprised by the sudden flare-up at the lake opined that the fire may not have happened instantaneously and must have been triggered by an external agent.
Dr TV Ramachandra, lead scientist of Energy and Wetlands Research Groups in the Centre for Ecological Sciences of Indian Institute of Science (IISc) said, "The fire could have happened because of two factors; The increasing amount of phosphorus that has been entering the lake through detergent water and untreated industrial and domestic waste containing oil and combustible chemicals."
Dr Ramachandra said the phosphorus and other combustible chemicals have integrated themselves into the sediment of the lake.
"The recent rains would have caused a churning and flow of fresh water would have disturbed the sediment, which would have come to the surface. Some of it has broken into black particles which are visible on the froth. Increased entry of untreated sewerage water into lake bed resulted in an unaerobic condition (absence of oxygen). When the oxygen is cut off, toxic and combustible gases develop over the surface of water which is covered with froth. Somebody may have thrown a cigarette or burning material into the lake causing the froth to catch fire," he said.
Another expert at the Karnataka Pollution Control Board (KSPCB) said the absence of wetlands aropund the lake may have aggravated the situation.
"These wetlands used to act as purifiers. But all such wetlands surrounding the lake have been encroached and there is no place for natural purification. Hence the pollution at these lakes is uncontrollable," the officer said.
Dr Ramachandra blamed the callous attitude of the people for the intense pollution in the lake. "Besides using increasing quantity of detergents, several home makers and hoteliers dispose of oil and other chemicals through wash drain which is directly let into the lake. The oil floats on the surface of water and accumulates densely under the froth," he said.
Following the incident, Bengaluru North tehsildar, former corporators and BBMP officials visited the spot. People from the localities around the lake mobbed the officials and vented their ire on them for failing to check pollution.