No clue yet on source of yellow discolouration in Periyar near Pathalam
The Hindu
Preliminary observation by PCB says algal bloom might have caused discolouration, though the board did not rule out presence of pollutants
The State Pollution Control Board (PCB) has not yet identified the source of pollution after the stretch of the Periyar close to the regulator-cum-bridge reported discolouration from January 15.
The area near the lock shutter of the regulator-cum-bridge appeared yellow in colour following suspected illegal discharge of pollutants. The PCB, which took samples, made a preliminary observation on Friday that algal bloom might have caused discolouration, though it did not rule out the change in colour owing to the presence of various pollutants.
Tests have revealed the presence of Trachelomonas algae. The results of other parameters, including nitrate and toxic chemicals, if any, have not yet been ascertained as the process is on, according to board officials in Ernakulam. The presence of Trachelomonas indicated heavy organic pollution. A similar discolouration was reported at the same spot in March 2022.
Though the PCB had then said that clandestine discharge from industrial units directly or through stormwater drains could cause pollution, no major follow-up action was taken. The enforcement agency lacked facilities such as underwater camera, and it did not seek the services of expert divers to check whether there were illegal outlets directed from industrial units into the river.
Some units have been authorised to discharge treated effluents in prescribed concentrations into the river. However, the board has not been able to ensure that the discharge of effluents is within the prescribed limits.