Low dissolved oxygen levels detected in Edamula branch of Periyar

An assessment by the Kerala State Pollution Control Board (PCB) has found low dissolved oxygen (DO) levels in water samples collected from Thumbunkal stream and Puthalamkadavu in the Edamula branch of the Periyar near Kalamassery.

The declining DO levels indicated poor water quality due to pollution from excess organic matter and illegal discharge of untreated wastewater. The region had witnessed incidents of fish kills on several occasions in the past two years.

The samples were collected on June 2, 2025 from Thumbunkal stream and Puthalamkadavu in the Edamaula branch. The PCB mentioned its finding on low DO levels in its updated status report on short-term measures under the Periyar River Action Plan submitted before the Ministry of Jal Shakthi in September.

The board had informed Kalamassery municipality about the declining DO levels found in water samples collected from Thumbunkal stream and the Puthalamkadavu in the Edamula branch. It said that there was a possibility of wastewater from the Kalamassery market reaching the river.

The report said that the municipality had completed the construction of the dumping yard and retaining wall as part of steps taken to prevent the flow of leachate from the dumping yard into Thumbunkal stream. The construction of compound wall was also completed, it said.

The State Level Monitoring Committee appointed by the National Green Tribunal had earlier observed that the discharge of untreated sewage from the Kalamassery township, wastewater from the Kalamassery market, and leachate from the local body’s waste dumping yard at North Kalamassery had resulted in fish kills in the Periyar.