Five days of idol immersions as part of Ganesh Chaturthi festivities has taken a toll on the 36 lakes across the city. The situation was so grim that the Bruhat Bangalore Mahanagara Palike cut access to immersion ponds in the Yediyur lake and Sankey tank.

According to BBMP figures, Yediyur lake saw the maximum number of immersions with more than 1.25 lakh Ganesh idols being immersed there. In west Bangalore, around 1.1 lakh idols were immersed in Sankey tank over five days.

BBMP officials said immersion would be allowed after Wednesday.

“There is no more space available in the immersion ponds at these two lakes. We have to clear the ponds to allow more immersions,” an official said.

At Ulsoor lake, around 91,000 idols were immersed. On Monday, BBMP workers were busy cleaning up the mess in the immersion area. But there was as much mess on the pavements around the lake, where plastic waste was strewn.

Pointing to the oily sludge, Ramesh, a worker, said, “We have been working on this since morning, but there is a lot to be cleared… It isn’t easy.”

The Karnataka State Pollution Control Board (KSPCB) had at least a dozen mobile immersion tanks in the city to provide citizens with an alternative. However, the sludgy aftermath in and around the lakes, including pieces of plaster of Paris idols, indicates that drives to popularise the use of clay idols have not worked as well as the authorities hoped.

V. Poojary, who lives by the side of Ulsoor lake, said even many people in his apartment used painted Ganeshs. “It is strange that they do not even care for their own lake. The size of idols keeps increasing as the whole thing is turning into a display of affluence,” he lamented.

The KSPCB is yet to collate figures. In 14 regional offices across the city, samples are being collected to study the impact of immersions on lakes, officials said.

Last year, some studies had roughly indicated that toxicity levels in lakes increase during immersions.