Rejuvenated lakes saddled with poor-quality water

In the months after the rejuvenated Kalkere, which is spread over 105 acres, was ‘formally’ inaugurated, residents of the area have been on their toes trying to keep their lake clean.

Kalkere joins a growing list of lakes in the Hebbal valley, a series of 37 lakes on the north and eastern peripheries, that has seen rejuvenation programmes. Of the 37, at least 20 have been rejuvenated. However, just three are of ‘good quality’, reveals an Indian Institute of Science (IISc.) report, which took an in-depth look into the issues plaguing the series of lakes.

Though the recent rains have filled Kalkere to the brim, for months residents battled civic authorities to stop inflow from a nearby Sewage Treatment Plant.

“The Bruhat Bengaluru Mahanagara Palike had created a sewage bypass along the lake. But it had breached in multiple locations. During rains, the sewage mixed with the lake water,” alleged a resident.

Once the breaches were attended to, they had to confront solid waste. Almost every two weeks, despite the lake being fenced, residents gather in groups to clear plastic bags and other debris from the banks. “The gates haven’t been completed. Often, we see vehicles entering the walking track to dump garbage. There are not enough home guards, who find it difficult to traverse the 6.7-km walkway to curb this menace,” said a resident.

The neglect of lakes after rejuvenation seems to be a recurring theme for Hebbal valley, arguably where most of the lakes have received some attention compared to the Vrishabhavathy and Koramangala-Chalaghatta series of lakes.

The 14th edition of the ENVIS technical report by the Energy and Wetlands Research Group of IISc. studied water quality and the land use changes in this 207-sq.km. valley series. Over 100 million litres of sewage flows through the valley untreated, leaving all but three in good shape. Even restored lakes, such as Kogilu, Hebbal and Gangadharakere, are turning into sewage cesspools with garbage lining their banks due to poor maintenance, notes the report by T.V. Ramachandra and his team.

While recommending an integrated watershed management to restore the biological and hydrological benefits derived from these lakes, the report notes: “(There has to be) restrictions on dumping solid waste and letting of untreated water… Any untreated water must be let through constructed wetlands as being done in Jakkur lake,” states the report.

Deputy Conservator of Forest (DCF), BBMP lakes and forest cell, Jagannath Rao said while funds for maintenance of lakes may be inadequate, they encouraged the participation of citizen groups and NGOs to keep an eye on restored waterbodies. “We do have mechanisms to ensure that sewage bypasses lakes. But, considering that all the storm-water drains carry sewage, there is some amount of sewage inflow that is unavoidable. This amount is low in rejuvenated lakes, which hold a lot of rainwater,” he said.

Treated water

Incidentally, treated water from SWDs is being diverted to Chickballapur for irrigation. Treated water will be pumped through stations at Hennur towards tanks in Devanahalli and Chickballapur.

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