Environment activists intend filing a contempt plea against the Calcutta Metropolitan Development Authority (CMDA), the custodian of Rabindra Sarobar, for its failure to keep thousands of people from performing Chhath Puja rituals in the lake over two days.

“This was a gross violation of the National Green Tribunal’s order and I will move a contempt plea next week against the CMDA and police for their failure to implement the restriction. I will also demand that an inter-departmental committee be given the responsibility for the upkeep of Rabindra Sarobar,” said Subhas Datta, one of the petitioners in the public interest litigation that led the green tribunal to prohibit “any puja, community picnic or organisation of other social events in and around the Rabindra Sarobar lake”.

According to Datta, a long-time campaigner against noise, air pollution and traffic-choker rallies in Calcutta, the Central Industrial Security Force should be given the responsibility of protecting Rabindra Sarobar instead of police.

Several green activists said the environmental quality of the lake had significantly deteriorated because of the administration’s failure to protect it from violations like those seen on Tuesday and Wednesday.

Citizen Initiative, a not-for-profit organisation, had first moved the high court in 2011 to demand the restoration of Rabindra Sarobar’s “environment quality”. Datta then joined the legal battle and the case was transferred to the National Green Tribunal. An expert committee formed by the tribunal and headed by the state biodiversity board’s chairman, Ashish Sanyal, recommended that puja rituals be prohibited at Rabindra Sarobar.

The green tribunal notified the restriction in 2017, but the state government requested that the order be enforced from this year. A fresh petition to extend the concession was rejected.

As the two days of Chhath Puja showed, the order was implemented only on paper. A police contingent stood by as thousands of devotees converged on Rabindra Sarobar and performed rituals in the lake.

“There was water, air and noise pollution. Firecrackers were burst. The lake was filled with waste (this was later cleaned),” said environmentalist S.M. Ghosh, a regular visitor to Rabindra Sarobar.

The NGO Sabuj Mancha said many small Chhath processions burst banned chocolate bombs and other crackers across the city. “We have

received about 20 complaints in two days,” said Naba Dutta, the secretary of Sabuj Mancha.