The water quality parameters along the Aluva-Eloor and Pathalam stretches of the Periyar failed to comply with norms of the National Water Quality Monitoring Programme in 2023.
The monitoring was done as part of the programme implemented by the Central Pollution Control Board in association with the Kerala State Pollution Control Board as part of the national-level monitoring of critically polluted river stretches in the country.
On the Aluva-Eloor stretch, the minimum dissolved oxygen level was recorded as 3 mg/litre against the desired level of 5 mg/litre and above recommended for optimum fish health. The biological oxygen demand was 3.2 mg/litre. The locations in which BOD exceeded 3.0 mg/litre are identified as polluted locations. The dissolved oxygen level at Pathalam was 4 mg/litre while the BOD was 3.9.
The report said the range of faecal coliform values in both the locations exceeded the primary water quality for outdoor bathing notified under the Environment (Protection) Rules, 1986 (maximum permissible limit of less than 2500 MPN/100 ml) in 2022 and 2023 at both the locations.
The range of faecal streptococci values also exceeded the primary water quality for outdoor bathing notified under the Environment (Protection) Rules, 1986 (maximum permissible limit less than 500 MPN/100 ml) in 2022 and 2023, it said.
On the Aluva-Eloor stretch, the faecal coliform value was 7900 MPN/100 ml while the faecal streptococci value was 940 MPN/100 ml. At Pathalam, the corresponding figures were 7000 MPN/100 ml and 1200 MPN/100 ml.
