Thousands of fish die in Doddagubbi lake

Thousands of fish have died in Doddagubbi Lake, a 125 acre water body in Bengaluru’s Mahadevapura Assembly constituency, after polluted water entered the lake during recent rains, with officials suspecting a sharp fall in dissolved oxygen.

Dead fish were found floating across several parts of the lake and along its edges, leading fisheries officials and the Karnataka State Pollution Control Board (KSPCB) to collect water samples. The samples have been sent for laboratory testing, which will determine the nature and extent of the contamination.

B Chikkanna, deputy director of the Fisheries Department in Mahadevapura ward, said the initial assessment pointed to asphyxiation caused by oxygen depletion. “Prima facie, the fishes died due to asphyxiation. Due to the rains, a large quantity of rainwater mixed with polluted water from Mittaganahalli GBA dumping yard entered Doddagubbi Lake, causing a shortage of oxygen,” Chikkanna told Hindustan Times on Sunday.

The department has begun an inquiry into the deaths and collected samples from the lake. “We have launched an investigation and taken samples,” Chikkanna said.

KSPCB regional officer K S Sudhakar said the lake appeared to be heavily contaminated during the initial inspection. The board has sent the samples to its laboratories for testing.

“We have taken water samples from the lake. We have already sent them for testing to our labs. Prima facie, it seems highly polluted and unfit for any kind of usage,” Sudhakar told Hindustan Times on Sunday.

Bengaluru Development Minister Krishna Byre Gowda has directed officials to inspect the lake and take corrective measures.

The fish deaths have also brought attention to the drainage network around the lake and the possibility of sewage entering the water body during rainfall. Environmental activists have alleged that untreated sewage may have entered the lake and worsened its water quality.

Former KSPCB chairman Dr Sharath Chandra said untreated sewage can rapidly reduce oxygen levels in a water body. Organic matter in sewage is broken down by microorganisms, which consume dissolved oxygen in the process. If oxygen levels fall sufficiently, fish can no longer survive.

Officials are expected to examine the drainage network around Doddagubbi Lake alongside the laboratory testing to establish how polluted water entered the lake.

The final cause of the fish deaths will be determined after the KSPCB laboratory reports are received.