Decline in dissolved oxygen level led to massive fish kill in Kerala's Eloor: PCB

As per preliminary investigations, the fish died as the DO levels in the downstream decreased with the sudden and continuous flow of DO-depleted water from the upstream.
Image used for representative purpose
Image used for representative purposePhoto | Express

KOCHI: The Kerala State Pollution Control Board has submitted before the High Court that the opening of the Pathalam bund’s shutter with the discharge of a high organic load likely caused a decline in dissolved oxygen (DO) levels in the downstream areas of the Periyar river, and led to the recent massive fish kill.

As per preliminary investigations, the fish died as the DO levels in the downstream decreased with the sudden and continuous flow of DO-depleted water from the upstream and the sludge of high organic load from the bund. The prolonged closing of shutters may cause the accumulation of organic load in the upstream. Therefore, instructions were issued to the irrigation department in January to maintain a minimum flow in the river.

However, the department neither took action nor informed the Board or other relevant departments regarding the opening of the shutters. It was mandatory to maintain the environmental flow in the river during the lean period, especially at the stretch where controlled waste disposal is permitted for industries.

The report was formed based on the preliminary probe and lab results. A few more analysis reports are awaited. It also stated that, at present, five industries have been permitted to discharge treated effluent into the Periyar river. During the inspection on May 21, illegal or untreated waste water discharge from these industries was not noticed.

It was observed that during the summer, when the bund is closed for a long time, organic waste reaches the river from several residential or commercial areas, ultimately depositing at the river bed of the upstream side of the bund. At the time of the bund closing, the treated effluent discharged will not be diluted enough due to the stagnation of the river. This may cause accumulation of organic load in the upstream.

The PCB filed the affidavit in response to a petition filed by K S R Menon and others seeking immediate steps to curb the discharge of toxic effluent by the industries functioning on the river bank.

The Board also suggested the formation of a committee consisting of the officials of the irrigation department, PCB and the Eloor municipality, and the laying down of a protocol for operating the regulatory-cum-bridge at Pathalam. The irrigation department should coordinate necessary action in this regard.

Suggestions in report

  • Action of the irrigation department for the construction of the walkway, dyke wall at the Periyar river bank at the industrial belt to have better surveillance and effective control of industrial discharges should be expedited

  • Industries department shall provide a proper drainage system for stormwater discharge and maintain internal roads inside the industrial area

  • Constitute a joint committee including the heads of revenue, fisheries, irrigation, PCB, LSGD, and industries departments to prepare a comprehensive action plan for specifically addressing the Periyar river pollution

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