Where does the Idol go after the celebration?

The drum rolls, the crowds disperse but the environmental impact of Ganpati visarjan can live on, long after the last procession.

For millions of Ganesh worshippers, visarjan is the emotional culmination of Ganesh Chaturthi, as the idol is taken back to water to say goodbye to Ganpati Bappa. But in increasingly choked cities, that has also become a major waste-management and pollution challenge.

This year has seen the early immersion days give a peek at what happens after the celebrations.

In Thane, 20,703 Ganesh idols were immersed during the first one-and-a-half-day immersion period, according to the municipal corporation. Nearly 9,600 idols were of clay, while around 18.6 tonnes of nirmalya — flowers and other offerings had been scraped out of the immersion process. They would go to processing, while plastic was to be recycled and disposed.

But the effects of these materials can live on in natural water bodies.

Idols made of Plaster of Paris (PoP), certain paints, plastic and thermocol decorations, along with such materials, can contribute to water pollution when immersed. Decorative materials, paints, plastic, thermocol and other non-biodegradable materials can linger after the idol has been immersed. India's pollution-control apparatus has promoted using clay idols, artificial immersion facilities and separate collection of puja waste to tackle this. The Central government has also recognized that idol immersion could affect water quality and aquatic life if the guidelines are not followed.

Mumbai provided a striking example this year. After the first immersion, flowers, puja material, plastic and other waste were reported around the Gateway of India , the obvious question, then, once the celebrations are over is, where does it all go?

At Vasai Fort, it was even more pronounced as several immersed Ganesh idols had been found near a jetty, raising the question of idol handling. Local residents and activists allege that idols had been dumped there. But the Vasai police had another version, saying that they hadn't been dumped but had washed ashore. The circumstances were disputable.

A further type of pollution associated with the visarjan is noise.

In Thane, an anti-noise activist recorded levels of 95-100 decibels near an immersion site. While DJ and Dolby use has reportedly declined from previous years, sound amplifiers, banjos and multiple drums added to the noise during the immersion processions.

But not all the environmental problems reported this week can be immediately attributed to Ganpati immersion.

In Pune, for instance, parts of the Mula river reportedly turned black and smelly, with dead fish seen as well. Authorities were analyzing the water, while residents allege that it was due to sewage and industrial pollution. There is no proof in the report that Ganpati immersion caused that incident, so it's important to not confuse correlation with causation.

Ganpati visarjan is a religious tradition, and the environmental question is what materials are immersed, where and what is done to the waste afterwards.

And with the major immersion day still to come on September 25, the real test for cities now comes. Can they ensure that the farewell to Ganpati is not a burden to the rivers, lakes, seas and communities receiving it?

Because when the idol disappears under the water, the environmental story doesn't end.