Oil spill from Mettur plant spreads deeper into Cauvery, raises safety concerns for drinking water

COIMBATORE: An oil spill from the Mettur Thermal Power Plant (MTPT), triggered by a coal bunker collapse, has spread out to a vast stretch of the Cauvery river, raising concerns about aquatic life, winged visitors, and also possible contamination of drinking water.

“As several drinking water pumping stations are located downstream from Mettur in the Cauvery river stretch, the flow of contaminated water, probably containing toxins, should be restricted immediately. Minimal traces of oil have already reached Chekkanur barrage in the mainstream Cauvery. Necessary water quality tests should be done to ensure the safety of the drinking water. Even though a cleanup is under way, it should be done scientifically as the oil spill is gradually entering the mainstream river,” claimed a study by Suzhal Arivom, an NGO.

The oil spill was first noticed by local people on December 20, and a field study by environmentalists on December 23 revealed its spread to around one km. This seems to be the first instance of an oil spill in this region and it is impacting Cauvery’s ecosystem. Unlike marine oil spills, which appear thicker because of the high density of the salt water, oil spills dissolve quickly in freshwater because of their low density and form a thin layer of oil on the surface of the water.

“A more scientific approach is necessary as thin oil coating can spread across a wider area in freshwater, making it difficult to determine by physical examination the extent of spread. As the dam is nearing its full capacity and with a likely release of water anytime soon, prompt clean-up and mitigation measures should be taken to minimise these impacts further downstream,” claimed the study's lead investigator, requesting anonymity.

Farmlands on the Cauvery surplus water stretch have already been impacted by a layer of oil settling on crops. It may also impact aquatic life, as around 36 indigenous fish species have been recorded in the stretch up to Chekkanur Barrage, where traces of oil have reached. Many rare and migratory bird species have been recorded by the Salem Ornithological Foundation in Mettur.

“To contain the oil flow, long floating booms, interconnected barriers, skimmers and absorbent pads should be deployed, rather than manual cleaning to effectively restrict the oil from entering the mainstream Cauvery river,” he added.

Meanwhile, an official with the MTPP said they have engaged local fishermen to remove the spilled oil.

“Using paddy hay, barriers were created to prevent oil from spreading from the stagnant water. The oil-mixed water was removed in ten tankers on Tuesday and 16 tankers on Wednesday. The spill was only in stagnant water and, perhaps, there is no possibility of it contaminating drinking water. We are desperate to adopt a scientific cleaning method, but couldn’t get access to those facilities,” the official said.

Two workers died in the collapse of the coal bunker on December 19.