KOCHI: While the coronavirus-induced lockdown has helped reduce air pollution, Ernakulam’s chief water source remains contaminated with high levels of coliform bacteria. Recent tests on samples from the Periyar showed an alarming presence of the pathogen.Samples collected from various stretches of the river revealed that Colony-Forming Unit (CFU) of coliform bacteria is higher than the standard prescribed even for bathing.
Pollution control board officials said CFU less than 100 per 100ml is considered standard for drinking water. For bathing, it should be less than 1,000 per 100 ml. But samples collected on April 10 from four different stretches of the Periyar painted a grim picture. Samples from near the Pathalam bridge and the bund upstream showed 1,800 CFU. Water from the bund downstream revealed a coliform bacteria presence of 1,600 while the Pathalam Kadavu sample had 1,700 CFU.
An official with the Kerala State Pollution Control Board (KSPCB) told TNIE that comparative studies were being conducted on pollution along the Pathalam-Eloor stretch during pre-lockdown and lockdown periods.“Results are yet to be out,” the official said. “But the recent sampling has revealed a high coliform presence. Direct consumption of water is dangerous. Even for bathing, water has to be chlorinated.”
The Biochemical Oxygen Demand (BOD) — the amount of oxygen required to decompose organic matter in one litre of water — is also high along various stretches in the Periyar. The BOD level increases if sewage mixes with river water, with around 3mg per litre being the standard. At Pathalam bund downstream, BOD was found to be 5.2mg. At Pathalam Kadavu, it was 4.8mg. However, the Pathalam bund upstream recorded a reduced BOD of 2.8mg.
“A high BOD represents the presence of more microorganisms. The Periyar is already listed among the four polluted rivers in the state,” an official said.The recent fish kills at Pathalam are attributed to low dissolved oxygen levels arising from pollution deep in the Periyar. When the average dissolved oxygen level should be around 6-8mg per litre, the units stood at 0.19, 0.58 and 4.9 at Pathalam bund downstream, Manjummel upstream and Pathalam bund upstream, respectively.
While residents claim discharge from the industrial area is causing the pollution and fish deaths, KSPCB blames the major irrigation department and civic bodies. The shutters of regulators are not opened regularly. Sewage discharge is also a cause for concern. District Collector S Suhas and the District Disaster Management Authority have entrusted KSPCB chief environmental engineer M A Baiju with the task of inspecting and taking action required.“We will visit all industrial units in the Eloor-Pathalam area from Wednesday,” Baiju said. “Strict action will be initiated if any industry is found discharging waste into the river.”