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Tuesday, Oct 22, 2019

Bengaluru lake froth on streets: Here’s what causes the toxic foam and how it is harmful to people

Videos showed cars disappear into plumes of foam on a road adjacent to the Bellandur Lake, where sewage and industrial discharge is believed to have created a concoction of chemicals that often creates froth.

india Updated: Aug 17, 2017 12:53 IST
HT Correspondent
HT Correspondent
Hindustan Times, New Delhi

Lakes frothing, catching fire and risking the health of entire neighbourhoods: Bengaluru has seen all these and more in the past decade as break-neck construction and poor urban planning choked waterbodies, filled them up with sewage and pollutants. Here are 10 facts to know about the city’s environment crisis.

1) The foam is toxic and reports say it is carcinogenic. It causes breathing difficulties, irritation on the skin, besides spreading an unbearable stench. Whenever it rains, the lake overflows, spilling the froth onto roads, blocking traffic.

2) A study at the Indian Institute of Science in Bengaluru, found that around 90% of the lakes in Bengaluru were affected because of the “sustained inflow of untreated sewage and industrial effluents”. In the infamous Bellandur Lake, for example, receives 500 million litres of untreated sewage.

Polluted Bellandur lake in Bengaluru on Thursday.
Polluted Bellandur lake in Bengaluru on Thursday. ( Arijit Sen/HT Photo )

According to a report by the Karnataka State Pollution Control Board, of the 67 lakes surveyed in Bengaluru, none had water that was fit for drinking. Local water conservation expert S Vishwanath said that some industrial effluents are harmful, “but it is domestic waste that we need to worry about because it forms 90 to 95 per cent of the waste that is dumped in lakes.”

3) The indiscriminate discharge of household waste and industrial effluents into lakes is what causes the toxicity, leading to the water body foaming.

4) Another thing to blame is detergent: Experts say the ubiquity of washing machines in urban India and indiscriminate use of detergent by households have come together to turn Bellandur Lake into a foamy disaster. Incidentally, around 40% of 1,800 households surveyed in eastern Bengaluru (where the water body is located) were found to be using at least five kg of detergent in a month.

Polluted froth from the Bellandur lake has entered houses along the water body in some areas.
Polluted froth from the Bellandur lake has entered houses along the water body in some areas. ( Arijit Sen/HT Photo )

5) Bengaluru’s lakes – about 600 large and small ones – have been the casualty of the city’s rapid expansion since 2001. According to Census data, the city’s population shot up from about 6.5 million to around 9.6 million between 2001 and 2011, an increase of around 50%. This made it India’s fastest growing city in that period.

6) A research paper titled ‘Impact of heavy metal contamination of Bellandur Lake on soil and cultivated vegetation’ says: “The study reveals that sewage is the main source of pollution of this water body and irrigation with sewage-contaminated water containing variable amounts of heavy metals leads to increase in concentration of metals in the soil and vegetation.”

7) Another paper, Rejuvenation of Bellandur lake, says: “There have been adverse environmental and public health consequences. The local community complained about the water borne diseases, contaminated bore well water (due to poor environmental conditions), etc. The committee is convinced of the problems faced by the local biological entities (humans, livestock, etc.) of serious water and soil contamination and consequent impacts in the food chain.”

Toxic froth from the polluted Bellandur Lake is blown into the air by wind in Bengaluru in this file photo.
Toxic froth from the polluted Bellandur Lake is blown into the air by wind in Bengaluru in this file photo. ( Reuters File Photo )

8) Apartment complexes that have come up in the past decade in Bengaluru are lined up across the bund of the lake. Between 2001 and 2011, the city’s population increased from 6.5 million to 9.6 million, the highest rate of growth of any city in India.

According to water conservation expert S Vishwanath, no place could deal with such a surge in population.

9) In 2015, foam from the lake spilled over on to roads and other spaces surrounding the lake. At the time, authorities insisted that the foam was from the detergents households discharged into the river. Last year in April, the froth on the lake had caused a traffic jam. More recently, on May 7, the city’s Bellandur lake caught fire. The resulting thick smog surrounded the heavily-polluted lake, making it difficult for the passers-by to breathe.

10) The National Green Tribunal has repeatedly criticised Bengaluru’s civic authorities for letting the city’s water bodies become, in effect, toxic waste dumps. The central body could find similarly mistreated lakes in countless other cities in India. Multiple sorts of wetlands are being lost due to urbanisation, changes in land use and pollution. What lakes have survived are shrinking.

Rapid urbanisation in Delhi NCR, for instance, is taking its toll. The expansion of impermeable surfaces like concrete roads and pavements is preventing the recharge of groundwater aquifers and blocking the flow from water channels to lakes.

Malavika Vyawahare and Vikram Gopal contributed to this report

First Published: Aug 17, 2017 11:48 IST

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