KOCHI: While the irrigation department and Kerala State Pollution Control Board (KSPCB) continue blaming each other for the Periyar pollution, the water quality test conducted by the latter reveals that decolouring has happened because of the discharge of sewage into the river. The laboratory test report was submitted to the state monitoring committee of the National Green Tribunal, state government and Ernakulam collector on Monday.
The KSPCB found that the sediment settlement in the Periyar is due to sewage intrusion. “The tests of the water samples collected from the Periyar reveal that decolouring did not occur due to the discharge of effluents from industries. The carbon dust found in the top layer was due to the operation of a boiler after a long time,” states the report.
The in-depth sampling showed that the dissolved oxygen (DO) level was very low in the Periyar. When the average DO must be 6-8 mg/l, the test revealed that DO in the upstream Pathalam bund was 4.9, downstream Pathalam 0.19 and upstream Manjummel 0.58. The river surface DO in upstream Pathalam was recorded at 6.20, downstream Pathalam 12 and upstream Manjummel only 2.4. The samples were taken from various river stations by the Environment Surveillance Centre of KSPCB at Eloor in March and April.
“Fish kills occur due to the low DO in the water. As water in the upstream mixes with the downstream, fish deaths are reported in the downstream as well,” an official said.Environmental engineer of KSPCB M A Baiju said civic bodies should be cautious about the flushing of untreated sewage and septage into the river.
“Our test could not find that de-colouring occurred because of the discharge from industries. There was a direction by National Green Tribunal in a case filed in 2015 that the minimum water flow should be maintained. However, after the bund was closed on March 30, it was reopened only on April 18. KSPCB had given several instructions to the major irrigation department, but most of them were not followed,” he said.KSPCB will take up the matter with the National Green Tribunal and seek action against the irrigation department and civic bodies if they fail to act.
Dissolved oxygen level in in-depth samples (mg/litre)
Pathalam bund 4.9
Pathalam bund 0.19
Upstream Manjummel 0.58
Dissolved oxygen atriver surface
Pathalam bund 6.20
Pathalam bund 12
Upstream Manjummel 2.4