Depleting oxygen levels have impacted fish population in the Muttar, a tributary of the Periyar.
The stress on fish population was experienced along the Edamula-Manjummel stretch on Tuesday. Water samples collected from the region by the State Pollution Control Board (PCB) showed that the dissolved oxygen level was 0.4 mg/litre against the required parameter of 6 mg/litre.
Though the board has not ascertained the exact reason for the declining level of dissolved oxygen, preliminary estimates pointed to the possibility of leachate flow into the Muttar from the waste dumping yard of the Kalamassery municipality in North Kalamassery. The release of raw sewage will also result in depleting dissolved oxygen levels, according to officials at the Environment Surveillance Centre of the PCB at Eloor.