ALAPPUZHA SEPT. 9. The Vembanad backwater system, which is the largest of its kind on the west coast of India, may soon turn out to be an ecological disaster due to the largescale pollution of its waters, indiscriminate exploitation of its resources and human intervention in the form of reclamation of land and other encroachments.
While the lake has shrunk to 37 per cent of its original area because of human intervention, the pollution levels have increased several-fold. Studies of the Centre for Water Resources Development and Management (CWRDM) have found that the solid content of the lake in several parts is abnormally high. There is an abnormal rise in faecal coliform count and high toxic level of water in certain areas.
The uncontrolled mining of shells from the lake is also posing a threat to the eco system. According to studies, the fish fauna and reptile wealth and molluscs found in the lake are facing a threat to their existence.
According to Dr. James of the CWRDM, the total solid content of the water of the Vembanad lake at the Kochi region has been recorded as a high 53,750 mg/litre during summer. He pointed out that the Kochi city alone emptied 2,550 million litres of urban sewage into the lake daily. He pointed out that the sewage contained pathogenic micro-organisms responsible for the outbreak of water-borne diseases such as Typhoid, Cholera and Dysentery affecting human beings and various diseases affecting the fish wealth.
According to experts, the sewage effluents and the heavy load of organic material released into the water are responsible for the decrease in dissolved oxygen content in the water in the lake.
It has to be noted that periodic outbreak of the above epidemics occur in Kuttanad and other areas along the sides of the Vembanad lake in Alappuzha district. Recently, a study conducted by the health department at Varanad and Muhamma areas had found that the pollution of Vembanad lake was the main reason for the occurrence of cancer among a large number of people in Thannermukkom, Muhamma and Varanad areas.
Dr James notes that 260 million litres of trade effluents reach Periyar estuary, a part of the lake system, every day from the industrial belt of Kochi. `Here the water is highly acidic and loaded with ammonia, fluorides and phosphates,' he points out. In the parts of the lake along the coastal areas of Alappuzha district, coconut husk retting and associated operations contribute heavily to the organic pollution load.
Dr .James observes that the Thannermukkom barrage had created a number of water quality problems such as restricting the flushing action and thereby making the upper portion of the Vembanad lagoon a bowl of agrochemicals and faecal matter and accelerating the growth of weeds such as the water hyacinth.
On the pollution of the lake in the Kuttanad region, Dr James noted that the major cause of pollution is the overuse of agro-chemicals especially pesticides. He noted that the annual fertilizer consumption in Kuttanad alone was around 20,000 tonnes. Fr. Thomas Peelianikkal of the Kuttanad Vikasana Samithi, which has started a campaign to clean the lake, pointed out that a large number of houses in Kuttanad did not have latrines. `Even those houses which have latrines empty it into the lake, he said.
Analysing the effects of pollution on the fish wealth, Fr. Peelianikkal said periodic outbreak of fish disease was common in Kuttanad region of Vembanad lake. Dr James noted that the estuarine crocodile found in Vembanad lake had been ruthlessly hunted down to near extinction and was found only in a few isolated areas at present.
Industrial dredging of the sub-fossil lime shell to a depth of 7 m had made the lagoon bed unsuitable for the growth of black clam, he noted. He added that the destruction of the mangroves along the sides of the lake was also destroying the ecosystem.
