17 City lakes poisoned, polluted

Environment Day: Eco-shock for Bangaloreans

A recent study by researcher Aboud S Jumbe and Dr N Nandini, reader and principal investigator, has revealed that nearly 17 lakes, including those rejuvenated recently, are contaminated with heavy metals like cadmium, chromium, copper, iron, manganese, lead, nickel and zinc, which makes the water impossible to use even for industrial purposes.
The heavy metal contamination is so high that it has exceeded the permissible limits to a greater extent. “ For example the permissible limit of cadmium is 0.12 microns, but the metal content found has exceeded to an alarming level. This might deteriorate the lakes,” said Aboud.

Aboud surveyed about 32 lakes in and around Bangalore during his five years study using an advanced computer module.  He said almost all the lakes including those like Hebbal, Ullal, Hulimavu, Agara, Iblur, Hoskote, Madiwala and Vengianakere which have been rejuvenated recently are also not in good state.

“We have classified these lakes as excellent, good, fair, poor and very poor. None of the lakes including the rejuvenated ones come under excellent and good, while Kengeri, Yelemallappa lake, Bellandur, Byramangala, Varthur, Malathahalli, and Karihobanahalli lakes fall in the poor category. Two lakes, Arekere and Shivapura lakes are in very poor category as they have been polluted badly,” explained Aboud.

Dr Nandini says that the sources of contamination are agricultural run offs, effluents from industries including pharmaceuticals. Under such circumstances, E.coli bacteria, which comes from a sewage waste will reach unsafe level in the view point of pisciulture. Fish intestine will have pathogens.

“Most of these inlets through which the pollutants enter the lakes, pass the industries and even agriculture regions. That is how they end up in these lakes,” she said.
She suggested lake conservation measures inside the lake such as removal of eutrophication, deweeding and bioremediation control.

Outside the lake, the measures suggested are preventing the erosion of the bank slope by afforestation programmes, improvement of drainage, control of sewage waste, solid waste management, watershed management , shore line management and establishment of protected parks around them.

The silver lining is that the water bodies in the outskirts of the City are in good conditions with aquatic plants like water lily. These are indicators of health, and are still blooming in lakes like Kittohalli, Bhimanakuppi and Kenchanapura lakes en route Big Banyan tree.