Three months after detecting alarming levels of faecal contamination, the ecological condition of Perandoor and Edappally canals continues to be on the decline.
Tests results of samples taken from five new monitoring stations on March 15 by the State Pollution Control Board revealed that the total coliform count, indicating faecal contamination, has exceeded the maximum permissible limits by 320 times in Perandoor canal. In Edappally canal, the maximum permissible limit was breached by nearly 230 times.
The Hindu had reported on January 28 that the total coliform count had exceeded the maximum permissible limits by 160 and 96 times respectively in Perandoor and Edappally canals. The tested samples were collected between December 9 and December 23 last year. The spike in coliform count shows the indiscriminate discharge of septage into the two major canals.
According to the Central Pollution Control Board, the maximum permissible limit of faecal coliform in water used for organised outdoor bathing is 2,500 cfu/100 ml, while the desirable value is only 500 cfu/100 ml.
The coliform presence in samples collected from Kattakara Canal Road near the Greater Cochin Development Authority’s LIG colony and Pachalam bridge along the Perandoor canal was 8,00,000 cfu/100 ml, which was nearly 320 times higher than the maximum permissible limit. The worst level of faecal contamination in Edappally canal was detected at the monitoring station at Chembokkadavu bridge. The coliform presence here was 5,80,000 cfu/100 ml, nearly 232 times higher than the maximum permissible limit.
The total coliform levels in the other monitoring stations were Lulu Mall (4,00,000 cfu/ml); Civil Lane Road near Padivattom (3,50,000 cfu/100 ml); Indiraji bridge, Muttar (1,40,000 cfu/100 ml); and Thuthiyoor bridge, Palachuvadu (1,10,000 cfu/100 ml).
The faecal contamination in the remaining monitoring stations in Perandoor was no different. At Sastry Nagar bridge, it was 4,80,000 cfu/100 ml while the corresponding figures were 3,50,000 cfu/100 ml at Elamakkara and 2,00,000 cfu/100 ml near the railway overbridge in Gandhi Nagar.
The Biological Oxygen Demand (BOD), a proxy for organic pollution, was higher than the ideal limit of 3 mg/litre prescribed by the Central Pollution Control Board in samples collected from both the canals. The BOD levels in the five monitoring stations in Edappally canal ranged from 8.1 mg/litre to 26.9 mg/litre, indicating the deteriorating ecological condition of the canal. The corresponding figures in Perandoor canal ranged from 5.2 mg/litre to 16.7 mg/litre.