Frequent instances of change of colour and odour and fish kill in the Eloor-Edayar stretch of the Periyar cannot be addressed unless the Irrigation Department ensures minimum flow in the river, the State Pollution Control Board (PCB) has said.
Major pollution-related problems in the river are noted during the summer season after the closure of Pathalam, Manjummal and Purapallikkavu regulators. They include change of colour of water to black upstream of the regulators, odour, and fish kill owing to lower dissolved oxygen levels. The Irrigation Department has to ensure minimum flow to avoid stagnation of the river, pointed out a report submitted by the board before the Southern Bench of the National Green Tribunal (NGT) on June 10.
The PCB maintained that the main sources of pollution in the Edamula stream of the river were the leachate flow from the Kalamassery municipal market and the solid waste dumping yard at North Kalamassery. Inspections revealed that high organic load from wetlands near the Naval Armament Depot at Kalamassery reached the river through Thoombungal and Edappally canals.
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The main reasons for fish kill at the Manjummal bund and Edamula stream are oxygen depletion and stagnation due to the closure of shutter and accumulation of organic load. The pumping stations of all industries and institutions in the region are located along the Edamula stream. The restriction of environmental flow and intake of high volume of water for industrial, commercial and domestic purposes result in drop of water level, said the report.
On the pollution of the Edayattuchal paddy fields in Edayar, the test results of water samples collected from the area showed discharge of untreated effluents into the canal. The PCB has requested the Irrigation Department to make the concealed drain connecting the Edayattuchal paddy fields and the Periyar accessible for conducting a detailed inspection.