Bellandur Lake, the largest lake in Bengaluru, was once the lifeline for the surrounding 18 villages – its water was used for irrigation and drinking purposes.

In happier times, the people of Bellandur and nearby areas celebrated ‘Theppotsava’ – an annual boat festival.

The lake was also part of a natural cycle. It had clean water during the monsoons and would then turn shallow or dry during the summers.

Now, though, it has become something of a sewage tank because of untreated sewage water entering into the lake through various inlets. It is today covered with weeds and filled with silt. This has led to the disappearance of aquatic life from the lake.

In theory, clean rainwater from nearby Koramangala and Challaghatta Valley should flow to Bellandur Lake through stormwater drains. However, due to the improper sewage system and a lack of effluent treatment plants, the sewage inflow continues.

The problem began in the 1980s. But with 14 industries in the vicinity and improved urbanisation, the problem escalated, which led to the High Court directing the Bangalore Water Supply and Sewerage Board or BWSSB to provide proper sewage network in the city to stop it from entering the lakes. The court order was not followed, and petitioners filed a contempt case, which is now pending in the Lok Adalat.

Only recently, the National Green Tribunal or NGT criticised the Government of Karnataka for not being able to protect the lakes in Bengaluru – it slapped a fine of Rs 50 crore and Rs 25 crore on the state and Bruhat Bengaluru Mahanagara Palike respectively. NGT went one step ahead and termed this an “environmental emergency”, calling Bengaluru lakes ‘septic tanks’.

And it wouldn't be wrong to say that. Bellandur Lake witnesses foam, especially during the monsoons when large volumes of rainwater mixed with sewage comprising chemicals and detergents enter the lake. In recent years, the lake has also gained notoriety for catching fire. This is said to have been caused by the cooking oil thrown from households that enters the lake. This oil spill produces methane, which cannot escape due to the foam.

A study conducted by the Indian Institute of Science in 2013 revealed that borewell water in Varthur village (close to Bellandur) was high in nitrate, ammonium, and phosphorous. Silver articles in the neighbouring houses turned black owing to the chemical nature of water, claimed residents.

People also complained of lung infection and skin allergy, and frequent dengue cases are also reported in the neighbourhood.

The problem is, only two sewage treatment plants exist currently that function to only 70 per cent of their capacity – at least two more are needed to deal with the incoming sewage.

The BWSSB says it has taken up the construction of two Intermediate Sewage Pumping Stations but claims finance as the main constraint for implementing the works.

So how do we fix the lake? Some of the recommendations that have been agreed upon widely are – decentralising water management, harvesting rainwater through interconnected lakes, decentralising treatment of sewage, stopping untreated sewage from polluting the lake, and most importantly, re-establishing interconnectivity of lakes by removing all blockades.

Authorities should take up this story of toxic froth and fire to rejuvenate Bengaluru's once-beautiful lake. Or risk losing a natural resource that's supported life for 130 years.

The choice, to us, is clear. Is it to those in power?