Discolouration of water continued in the Periyar on Sunday.
It was near the Pathalam regulator-cum-bridge that the change in colour was visible on the day. While water turned pitch black in one stream, it was milky near the regulator, said Adamkutty, a resident of Pathalam.
The change in colour, which was first noticed in the morning hours, continued till 2 p.m. Despite being alerted, officials of the Pollution Control Board (PCB) did not pay much attention to the matter, he complained.
The discolouration of the river system, which provides drinking water to Kochi city and adjoining areas, has been a cause for worry for residents. Moreover, environmental activists have been protesting against the pollution of the river and demanding steps for its protection. For the record, the pollution of the river system had earlier led to violent protests in the region.
Eutrophication
Meanwhile, P.B. Sreelakshmi, environmental engineer of the PCB’s Environment Surveillance Centre at Eloor, said the discolouration was due to the poor quality of water as a result of eutrophication.
When excessive nutrients reach the waterbody, it will lead to algal bloom. A few days later, algae will die and decay, resulting in a foul smell and discolouration of water. Water in some reaches of the river system has been stagnant. Reduced water flow in the system has added to the deteriorating water quality, she added.
According to her, huge quantities of organic load in the form of sewage from nearby townships are regularly reaching the river system.
On residents’ charge that the discharge of untreated effluents into the river from industrial units was causing discolouration of water, Ms. Sreelakshmi said the areas near industrial units were being regularly monitored, and that any change in water quality parameters could be detected immediately.
Incidentally, there are no industrial units near the Muttar area of the river where discolouration was reported the other day.
Same was the case last month. Eutrophication due to dumping of sewage should be blamed for that, she added.