On Sunday, when K Natarajan immersed a small clay Ganesh idol in a flower pot in his kitchen garden, he couldn't help but reminisce about his childhood. "There were a number of tanks and after the Vinayaka Chaturthi festival, we would immerse the clay idol in the water, symbolically letting it return to the earth," said the retired Chennai airport director who lives in T Nagar. "No water tanks are left so I now immerse the idol in a small pot," he said.

At least 11 major water bodies in the city and its suburbs have disappeared, forcing many residents to do the ritual immersion of Ganesha idols in buckets and pots. This time, some sent their idols along with groups headed to the Marina for idol immersion. The change indicates the rapid depletion of water sources in the city.

S Thiruvakarasu, a retired public works department (PWD) engineer who went to the Marina to immerse his idol, said there were 20 lakes in Porur and Arumbakkam alone. "All these lakes have disappeared over the years, which is why we now have floods during the monsoon. The groundwater level has also depleted because the lakes have dried up. The lake beds have been turned into colonies or have been encroached upon," he said. Public and private wells have also dried up.

Thirunavakarasu said a huge lake near Mambalam railway station has disappeared. "Till the 1960s, there was a lake near Nungambakkam, which was a major water recharge point. There were lakes in Pazhavanthagal, Ambattur, Avadi, Madipakkam and Puzhuthivakkam. A huge 150-acre lake near Adambakkam has now reduced to just five acres due to encroachments," he said.

Older residents of the city also recall the time when Vinayaka Chaturthi was a smaller festival with people using only small clay idols, which are ecofriendly . Bal Gangadhar Tilak transformed the festival into a large public one to unite people during the freedom struggle. S Ramachandran, an independent astro-meteorologist , said Tilak used the festival as a tool of protest against British, gathering huge numbers of people for the immersion ceremony . This form of the festival came to Tamil Nadu in the late 1980s and early 1990s.

P V Marimuthu, deputy director of Tamil Nadu Pollution Control Board , said clay idols are preferable to large painted idols that pollute water bodies when immersed. "We no longer have wells or other water bodies in the neighbourhood . So we should use only clay idols for sea immersion," he said.

