High coliform levels detected on four stretches of Periyar

Faecal contamination exceeded the maximum permissible limits along the four monitoring stations on the Periyar in Ernakulam from April 2025 to June 2025.

The total coliform count, indicating faecal contamination, recorded at the sewage discharge point in Aluva was 70,000 MPN (most probable number) per 100 ml, according to the test results compiled by the Kerala State Pollution Control Board. The maximum permissible limit of total coliform in bathing water, as prescribed by the Central Pollution Control Board (CPCB), is less than 2,500 MPN per 100 ml.

The analysis of water samples was done as part of the CPCB’s National Water Quality Monitoring Programme. Samples are collected from fixed locations on the Aluva, Eloor, Kalamassery and Pathalam stretches of the Periyar and every month as part of the monitoring programme.

The total coliform count along the Eloor stretch varied between 3,200 MPN/100 ml to 7,000 MPN/100 ml between April and June. At the sewage discharge point in Aluva, the total coliform count was 21,000 MPN/100 ml in April. At Pathalam, the corresponding figure was 5,400 MPN/100 ml in May. On the Kalamassery stretch, the total coliform count levels were 5,800 MPN/100 ml and 2,800 MPN/100 ml in April and May respectively.

The CPCB’s National Water Quality Monitoring Programme conducted between January and December 2024 had revealed that the water quality parameters at 13 monitoring stations along the Periyar in Idukki, Thrissur and Ernakulam districts had failed to comply with norms.

The analysis had revealed that all 13 locations failed to meet the primary water quality criteria for outdoor bathing, as notified under the Environment (Protection) Rules, 1986. The parameters of non-compliance included dissolved oxygen, pH, biochemical oxygen demand, faecal coliform, and faecal streptococci, according to the CPCB.