CHENNAI: Tonnes of fish and other aquatic life have been washing up dead along the Kosasthalaiyar River near the Ennore estuary since Saturday (August 15), with fishermen alleging that heavily contaminated industrial discharge that entered the waterway through the Buckingham Canal have caused the deaths.
With reports on the die-off coming in since Saturday morning, fishermen said the floating carcasses spanned nearly 6-7 km of the waterway, from the Buckingham Canal near Kattukuppam, past the North Chennai Thermal Power Station.
Fishers and the Save Ennore Creek campaign have pointed to thermal pollution from the hot-water discharge of NTECL Vallur as a possible cause.
They said a water-temperature study conducted on August 9 by Kattukuppam fishermen recorded temperatures of 40.8°C and 40.6°C at locations in the Railway Bridge Canal, 585-1,045 metres from the plant's discharge point.
They have now sought a detailed investigation to establish whether the discharge was responsible for the die-off.
The sequence of events also pointed to unusual water conditions, fishermen said. Around noon on Saturday, Kattukuppam fishermen casting nets near the Railway Bridge, about three hours into the falling tide, noticed unusually large shoals of fish.
By 5 pm, as the tide turned, fishermen using stake nets for prawns at Sandi koil, Manja machine, Jalli kuzhi and Subbaralam paadu, further along the creek, reported similar behaviour.
As the incoming tide pushed the creek water inland, dead fish were washed up towards Manali and Kattupalli, with extensive mortality visible across the creek by Sunday morning.
Fishers and Save Ennore Creek campaign have demanded an immediate halt to hot-water discharge from NTECL and North Chennai Thermal Power Station. They have also sought compensation for the damage to their livelihood and the implementation of the National Green Tribunal's July 2022 Ennore Creek eco-restoration order.
RL Srinivasan, president of the Fishermen Co-operative Society, Ennore, said fish deaths linked to suspected industrial discharge had been occurring frequently, but the scale of the latest incident was much larger.
"This has been happening frequently. This time, the magnitude seems much larger. Water mixed with chemicals is being released from the Manali side through a canal. It mixes with the backwaters and, during low tide, flows towards the sea," he said.
Fishermen allege that such potent discharges are being made during the night to avoid detection. They have now launched road blockades in Ennore, demanding action against the recurring pollution of the waterbody.
While officials from the Fisheries Department inspected the site, Tamil Nadu Pollution Control Board officials, who have yet to ascertain the reason for the mass fish deaths, said initial sampling tests have been completed and the results are awaited.
Madhanagopal, a fisherman from Kattukuppam, said the latest die-off was noticed around 11 am on Saturday and had extended several kilometres. "This is due to fertiliser factories. Because the contaminated discharges enter through the Buckingham Canal, the impact on our livelihood is huge," he said.
A range of fish and aquatic life, including madal, thullal, sankara, koduva and irunka varieties, besides prawns and crabs, had been found dead, he said.
"It first started with the release of hot water decades ago. Now, they are dumping all kinds of chemicals into the backwaters," he said, referring to industrial facilities in the Manali-Ennore belt.
Fishermen said such repeated incidents have been affecting their livelihood. As the community worries about sustaining themselves and educating their children, they have demanded immediate intervention to identify and plug the source of toxic discharges.