Ganesha Chaturthi festival this year has worsened the already deteriorating condition of lakes in the city.
Chemicals and other materials in Ganesha idols that were immersed in these water bodies have reduced the dissolved oxygen levels and increased the oxygen demand in the water, says the Karnataka State Pollution Control Board.
Based on an analysis of water samples in Yellemallappa, Ulsoor, Lalbagh and Yediyur lakes, the board found that the pH level of the lakes had increased by almost 20 per cent after the immersion of idols.
This, the release said, is due to the dissolution of clay, adhesives and paint from the idols.The quantity of dissolved oxygen (DO), which should be a minimum of 4 mg per litre for sustenance of aquatic life, has fallen by anywhere between 4 per cent to 70 per cent.
Along with this, the condition of the city lakes has also changed from ‘bad to worse’, says KSPCB as the biological oxygen demand (BOD) has shot up.
The activity has also shot up the levels of chemicals like mercury, cadmium, lead and chromium to non-permissible levels.
As a measure to improve the condition of the lakes, the board recommended better ways of celebrating the festival without causing harm to water bodies.
Among the suggestions were avoiding the use of non-biodegradable materials like thermocole, composting biodegradable material and avoiding immersing of flowers, food, coconuts and other material into lakes.