Residents, forest dept salvage Puttenahalli Lake

Amidst frequent reports of Bengaluru’s depleting waterbodies, and with some facing imminent wipe out from all quarters, residents of Puttenahalli in Yelahanka scripted history on Saturday.

They have transformed what was once puddles of sewage into beckoning nature -- a serene lake everyone can look forward to visiting in the coming days in North Bengaluru.

Now, with the rejuvenation of the lake almost through, the residents held a ‘Kere Habba’ - a community get-together in the lake premises to celebrate their decade-long struggle to rebuild the waterbody.

Despite being declared as a ‘Bird Conservation Reserve’ in September 2015, the lake was filled with sewage and had become a breeding ground for mosquitoes. But the rejuvenation work by the forest department along with the residents’ collective — a blend of technology with natural conservation methods has made the Puttenahalli Lake a model for lake rejuvenation in the state.

Unlike other lakes in the city, that take in treated water from elsewhere, Puttenahalli Lake will directly receive sewage and treat it at the experimental ‘Passive Conditioning Plant’ built on its premises, and then release the treated water into the lake.

The new technology put to test at the Puttenahalli Lake will ensure water in the lake through the year. Moreover, the lake will take in as much water as it requires thereby avoiding a situation like in Varthur or Bellandur, which often overflow beyond capacity.

To top it, with the rejuvenation work, the 15-hectare lake has only lost 0.1 hectare for the diversion canal and the treatment plant.

According to the residents, the method if adopted, will prevent pollution in all the lakes in the city.

Offering further insight, Prof H N Chanakya, from IISc’s Centre for Sustainable Technologies, who has worked on the plan said: “Due to the diversion channel, the raw sewage will not enter the lake. But the passive conditioning plant, with a capacity of 1 MLD (million litre per day), built at a corner of the lake abutting the sewage channel, will take in up to 1 MLD of sewage, and treat it naturally to replenish the water level in the lake. A balancing weir which is under construction will help control the intake. Hence, how much ever water you lose to evaporation, it is replenished by the plant. This will ensure water at the lake all through the year, besides helping to recharge the groundwater level in the vicinity.”

According to the locals, the entire rejuvenation work will get over by February and the lake will be dedicated to the public along with added attractions like a walkers’ and joggers’ path, bird watching points and gazebos. Planting of saplings both around the lake and on the island will also be taken up soon after.

The rejuvenation work would not have been a success without the forest department. The officials led by Dipika Bajpai, Deputy Conservator of Forests, Bengaluru Urban, worked relentlessly from planning to sanctioning of funds required for the rejuvenation project. C Jayaram, Principal Chief Conservator of Forests (wildlife) also helped in preventing the misuse of the lake premises, by adding the adjoining installations.

Ray of hope

S K Sangunni, a retired professor from the IISc, who is also the chairperson of the Yelahanka-Puttenahalli Lake and Bird Conservation Trust, said that their great struggle spanning several years is finally yielding results. “Starting from nowhere, at least we have come to a place where we now see a ray of hope. While the rejuvenation work is almost done, the abandoned sewage line of BWSSB, right in the middle of the lake bed, is still a worrying factor. We have been urging officials to shift it completely. Once the lake is opened, the only challenge would be the maintenance,” said the retired professor.