KOCHI: With environmental activists raising concern over the alleged release of effluent from chemical industries into River Periyar, the Irrigation Department on Friday released water from the Pathalam regulator. However, the river continued flowing in black hue, prompting protests.
The Committee against Periyar Pollution took out a protest march to the Pollution Control Board (PCB) office on Friday on the occasion of World Water Day, demanding steps to stop release of industrial effluents to the river.
According to the PCB, though the water in Periyar was found black, no fresh violation has been detected during the past couple of days. “When the water is released from the regulator, the water will be mucky. We are conducting regular inspections in the morning and night and no violations have been noticed. The Board has urged the District Collector to initiate action to clear the overgrowth on the banks of the river to monitor the drains opening into the river,” PCB environmental engineer P B Sreelakshmi told Express.
The PCB had conducted microbiological analysis of the water samples from Periyar with the help of the Cusat School of Marine Sciences after the water turned green last week. The results revealed that the colour was due to algal bloom. “The green colour was due to an algae called ‘platymonas sp’ usually seen in marine ecosystem. It will also produce algal toxin that severely lower oxygen levels in natural waters. After the life cycle, it decays and the water will turn black and grey spreading foul smell. This will also lead to dissolved oxygen depletion,” she said.
According to the PCB, accumulation of nutrients such as nitrates, phosphates and low water levels in inland waterways and lakes were the reason for the colour change.
“Stagnation of water without flow resulted in accumulation of nutrients and the increase in temperature caused algal bloom. If the flow is not maintained, this phenomenon will continue and can cause regular fish death in the lean period,” said Sreelakshmi.