65 city lakes contaminated: Report

65 city lakes contaminated: Report

July 17th, 2009
By Our Correspondent

Bengaluru
July 16: Bengaluru, which boasted of several lakes in the past, has very few left now. Even these are under threat due to various factors including encroachment of lake beds and unscientific discharge of sewage into the water bodies. A study on the quality of water by the Lake Development Authority (LDA) has revealed shocking facts: 65 lakes in the city were found contaminated with varied levels of nitrates and phosphates. “The report was submitted to Karnataka State Pollution Control Board (KSPCB) for required regulation on June 30,” said M.S. Gaudar, member secretary, KSPCB.
Of the 593 city lakes that come under BBMP, the BDA, minor irrigation department, zilla panchayat and forest department, the LDA has chosen 77 lakes for the analysis on quality of water.
“We have found all the 65 lakes to be contaminated with different levels of phosphates and nitrates. The next round of reports will be submitted on October 31, which will give a comprehensive picture of the city lakes,” said U.V. Singh, Lake Development Authority.
While nitrate levels are the highest in Kaggadasapura lake, the level of phosphates are high in 29 lakes including Kaggadasapura lake, Jaraganahalli lake and Madavara lake. It is highest in Bellandur lake, says the report.
“While the tolerance level of nitrate is 45mg/litre, for phosphate it is 5mg/litre,” says Dr Alka Singh, consultant biochemist at Apollo International. “If the nitrate level in water exceeds the tolerance level, it affects the function of the kidney and liver. It is disastrous to livestock,” she warns.
High levels of phosphate presence in water leads to renal failure, decrease in serum calcium that can result in Tetany-convulsions, she says adding that high levels of phosphate is dangerous for aquatic life.
Eighty per cent of the 870 MLD (million litres per day) water supplied by BWSSB is used for non-potable purposes, generating large quantities of sewage everyday. Only 15 per cent of this sewage is treated in treatment plants. The rest enter storm water drains, which are meant to route excess rainwater to lakes. The presence of detergents in sewage water causes phosphate contamination of lakes, which eventually leads to the growth of algae and water hyacinths, choking lakes to death.