Subscribe
Fishers and environmental activists have alleged that hot-water discharge from the NTECL Vallur thermal power plant may have contributed to the mass fish kill reported in Ennore Creek on August 15. They allege that the water release from Railway Bridge and Kuruvimedu canals are the sources of the fish mortality, based on the observation of the fishers’, tidal movements and water-temperature measurements.
The Save Ennore Creek group and fishers from Kattukuppam have demanded a detailed investigation to determine the cause of the fish kill. They have also called for an immediate halt to hot-water discharge from NTECL Vallur and the North Chennai Thermal Power Station into the creek.
The Railway Bridge Canal receives spent cooling water discharged from NTECL Vallur’s 3x500 MW thermal power plant. Local fishing communities have previously raised concerns over thermal pollution from the discharge.
A water-temperature survey conducted on August 9 by Kattukuppam fishers S Kumaresan and Raja Masilamani, along with volunteers from the Save Ennore Creek group recorded “aquatic heat wave-like conditions” at four locations between 585 metres and 1,045 metres from the plant’s discharge point.
Temperatures of 40.8°C and 40.6°C were recorded at two locations in the Railway Bridge Canal. The group said the readings were recorded nearly a week before the fish kill and could indicate prolonged thermal stress in the creek.
According to fishers, hot-water discharge from the plant is a daily occurrence and its impact becomes more pronounced during low tide, when there is less dilution. They said prolonged exposure to elevated water temperatures can increase fish metabolism and oxygen demand while reducing dissolved oxygen levels, potentially causing physiological stress and, at sufficiently high temperatures, mortality.
However, whether thermal pollution caused the August 15 fish kill has not yet been established. The Tamil Nadu Pollution Control Board (TNPCB) and Fisheries Department have collected water and fish samples for analysis.
TNPCB Chairman Anurag Mishra said that there were no visible signs of an oil spill or industrial effluent discharge at the site and that laboratory testing would be required to determine the actual cause of the fish mortality.
Fishers said the sequence of events on August 15 raised concerns about a possible connection between the discharge area and the subsequent spread of dead fish across the creek.
Around noon, Kattukuppam fishers using cast nets near the Railway Bridge, about three hours into the falling tide, reported unusually large shoals of fish. They said such movement was unusual for fish typically found in the river and creek.
By around 5 pm, after the tide had turned and begun flowing inland, fishers from Mugatwarakuppam using stake nets to catch prawns at Sandi Koil, Manja Machine, Jalli Kuzhi and Subbaralam Paadu reported similar sightings. Although the nets were intended for prawns, fishers said each reportedly contained fish worth Rs 15,000 or more.
The fish were allegedly sluggish and semi-conscious, according to the fishers.
As the incoming tide moved creek water inland, dead fish were subsequently reported towards Manali and Kattupalli. By the morning of August 16, extensive fish mortality had become visible across the creek.
Fishers from nearly eight villages around the Kosasthalaiyar River and Ennore estuary have estimated that four to six tonnes of fish, prawns and crabs may have died. Species reported among the dead include madavai (flathead grey mullet), kendai (carp), keluthi (catfish), oodan (silver biddy), neththili (anchovy), kelanga (ladyfish) and kola (garfish).
More than 8,000 families in Nettukuppam, Thalankuppam, Ennore Kuppam, Mugathuvarakuppam, Sivanpadi Veedhi Kuppam, Periya Kuppam, Chinna Kuppam and Kattukuppam depend on fishing in the area, according to fishing communities.
Fishers have also linked the incident to changes in the physical characteristics of the canals.
They said the Kuruvimedu and Railway Bridge canals were once wider and deeper and were fringed by mangroves. According to them, construction activity associated with the Vallur power plant and TANTRANSCO transmission towers has contributed to narrowing and siltation of the canals.
They argue that shallower and narrower waterways could reduce water circulation and dilution, potentially intensifying the effects of thermal pollution.
Fishers also alleged that water near the discharge point appeared greyer than usual, describing it as “cement-coloured”. They suspect that chemical effluents may have been discharged along with the hot water.
This allegation has not been established through official testing. The ongoing analysis of water and fish samples is expected to help determine whether any chemical pollutants were present.
The latest fish kill has also revived concerns among fishing communities about the long-term impact of industrial pollution on their livelihoods.
Fishers recalled the 2023 CPCL oil spill, saying fish and prawn populations in the creek took more than a year to recover. They fear the latest incident could similarly affect fish stocks and fishing incomes for months.
The Save Ennore Creek group and Kattukuppam fishers have demanded compensation for the losses suffered by fishing communities and called for the implementation of the National Green Tribunal’s July 2022 order directing the ecological restoration of Ennore Creek with meaningful participation from fisher communities.
They have also demanded that hot-water discharge from NTECL Vallur and the North Chennai Thermal Power Station into the creek be stopped pending a comprehensive investigation.
