Killing lakes for a living

The City’s lakes are increasingly getting contaminated due to inflow of untreated sewerage, encroachment of the lake beds by real estate developers is making matter worse.  The crisis in the making calls for immediate intervention.

The irony couldn’t be starker. At a time when the Cauvery water issue is on the boil and water disputes are hitting national headlines, Bangalore continues to give scant regard to critical natural water resources: Its lakes. And when the civic agencies are struggling to address the mounting garbage menace, the lakes remain polluted, contaminated by the unbridled flow of untreated sewerage.

The major lakes of Bellandur (Koramangala-Challaghatta valley), Byramangala (Vrushabhavathi valley) and Hebbal-Nagavara valley are soaked in sewerage and have turned toxic. The water is so badly polluted that it can be consumed neither by humans nor animals.

The increasing level of nitrogen and phosphorous in the waters of almost all the lakes has been confirmed by scientists at the Energy and Wetland Research Centre (EWRC), Centre for Ecological Sciences (CES) and Indian Institute of Sciences (IISc). The study conducted by a team of researchers headed by senior scientist Dr T V Ramachandra of EWRC says that the water in all the major lakes is mixed with sewerage water, leading to unaerobic conditions (no oxygen in water).

“There is high amount of nutrients available in the water. Due to this, there is  profuse growth of macrophyte (invasive species like water hyacinth). When this happens, no sunlight will penetrate into the water and there will be no growth of algae. Fish and other aquatic life will cease to exist,” explains Dr Ramachandra.

The contamination has also affected the groundwater in the City. The study has found the presence of nitrate and e-coli bacteria. “Both are present in high levels. It means sewage entering the lakes has contaminated the ground water. The health of the people drinking the water will be affected,” says Durga Madhab Mahapatra, a researcher who was part of the study.

He said sewerage was turning lakes into breeding grounds for mosquitoes. In places around the Bellandur Lake, people can’t even keep their doors open, because of this. Diseases such as chikungunya have come rampant there, he added.

According to Mahapatra, the change is happening so fast that in some lakes, the content of ammonia which was about 30 parts per million (ppm) has now reached 70 ppm. The aquatic life has virtually disappeared.

Many lakes on the outskirts of the City are contaminated with heavy metals released by industries in the vicinity. The plants uptake these heavy metals as is evident from the contamination of vegetables at Varthur and Peenya, Dr Ramachandra informed.

If the pollution levels had been low, the water bodies themselves would have been the solution. The lakes are capable of treating the sewerage naturally to a certain extent. However, the situation is so worse that the lakes have exceeded their capacity.

“Nature will treat sewerage. But we are letting sewerage in such huge quantity that it is crossing the threshold of the lakes’ ability to treat,” says a scientist. Bellandur Lake, arguably the city’s biggest and most polluted water body, does its job to treat water during monsoon till winter sets in.

The City’s sewerage flows in three directions and the lakes in all these valleys receive one-third of Bangalore’s sewerage. Several buildings have come up on the catchment areas of Bellandur Lake and the wetland is in danger of losing its existence. Based on remote-sensing data, the study has found that the lake is being filled up in most places.

The study says that the lake’s ability to remove pollutants has decreased to a large extent due to the anthropogenic activities, which include conversion of the watershed area into residential and commercial layouts.

“The conversion of the nearby wetlands and alteration of the landscape topology by filling up the low-lying areas and levelling them has affected the hydrologic regime of the lake,” says the EWRC study.

Construction debris

Even in the lakes in the Hebbal-Nagavara valley, construction debris is dumped in the lake bed area. The motive of the land sharks is to fill up the water body, so that it can be encroached and utilised for construction activities.

Dumping of solid waste is another cause which is choking the lakes in the City. With the problem of garbage disposal reaching the pinnacle, the lakes on the outskirts of the City are becoming targets of indiscriminate disposal of waste.

The effluent treatment plants and sewerage treatment plants set up around these lakes have not been effective. The burgeoning population of the City and reckless construction activities are sounding the death knell for the water bodies.

Only a few of the City’s 93 lakes can be termed “good” now. A good lake, according to Dr Ramachandra, is one which can provide good service by meeting the food (fish and ground water) and fodder requirement. Almost all the lakes do not meet these parameters.

Legal interventions

The matter being a cause of worry, several public interest litigations (PIL) were filed in the High Court of Karnataka. Following a PIL by the Environment Support Group (ESG) , the High Court had constituted a committee headed by Justice N K Patil. The committee comprised of nine top officials, including five IAS officers, three IFS officers and Leo Saldanha, co-ordinator, ESG.

The committee noted that intense pollution due to indiscriminate release of sewerage and improper maintenance were driving the City’s water bodies to extinction and had held even civic agencies like the Bangalore Development Authority (BDA) responsible for the present state of the lakes.

The committee also cited the A T Ramaswamy report of 2007, which had mentioned 2,488 cases of lake encroachment. As many as 1,848 acres of lake area had been encroached by land grabbers and builders by fabricating documents, according to the Ramaswamy report.