Bengaluru: Land use changes in the upstream, boosted by the ongoing work on the Shivaram Karanth Layout, are likely to bring additional flood water to the Puttenahalli lake.
Adding to this, the BBMP's stop-gap measure to channalise sewage and stormwater drain (SWD) in two separate pipelines under the walking path of the lake will have long-term implications.
Analysis of the land use change through the Google Earth images show that at least 400 acres surrounding the lake, most of it upstream, is undergoing a huge transformation. What were once farmland or uncultivated lands with grass are fast turning into paved areas.
"Development is fine as long as the authorities planning and approving it are taking steps to ensure that storm water and the sewage generated in these areas do not pollute the lake ecosystem. The development in the last two weeks does not give that confidence," said KS Sangunni, the retired IISc professor and chairman of the Yelahanka Puttenahalli Lake and Bird Conservation Trust (YPLBCT).
Last week, a stormwater drain (SWD) built by the Bruhat Bengaluru Mahanagara Palike (BBMP) without prior clearances from the Forest Department for the work inside the lake area, dumped sewage into the bird conservation reserve.
After the issue drew criticism from conservationists, the BBMP has decided to take the sewage and storm water from the upstream layouts through the walking path of the lake in two pipes. The two pipes will drain at the upcoming sewage treatment plant.
Interestingly, the Forest Department, in a letter dated May 15, advised the BBMP to get wildlife clearance before taking up work. Sources said the work has been taken up without permission.
"Who will bell the cat?" Sangunni said, noting that the flow of sewage into the lake was in direct violation of the Karnataka High Court order, referring to the December 2021 order related to Puttenahalli lake.
Retired Indian Railway Service of Engineers Officer Ajay Singh, who is working with the YPLBCT for conservation of the lake, said they have sought from the BBMP details regarding precautions taken to avoid seepage of sewage.
"Conversion of an SWD into a pipeline is unusual work. We sought details of the filtration process or any plans to ensure the sewage and the SWD pipe do not get blocked. We are yet to get an answer," he added.
BBMP officials have not clarified on how they plan to complete the pipeline work without damaging the outflow of the lake, which balances the water level.
BS Prahlad, BBMP Chief Engineer (stormwater drain), said work will begin next Monday. He could not be reached for a response to the concerns.