The west bank of Hooghly suffered large scale pollution as usual during immersion of Durga idols despite efforts by Howrah Municipal Corporation (HMC).

A visit to the ghats on Saturday morning revealed lumps of clay and straw floating in the water near Shibpur Ghat as were thermocol and other materials. Large bamboo structures, some with parts of the idol stuck to them, were seen lying near the jetty, along the banks of the river while some were stuck under anchored vessels.

Unlike the ghats in Calcutta, Howrah ghats do not have cranes to pull out the idols right after immersion. HMC employed a few labourers and underage boys to pull out the structures from the river. Such half-hearted, feeble attempts yielded little in terms of keeping the river clean.

HMC's disaster management department, conservancy department and Howrah City Police joined hands to organise a peaceful and pollution-free immersion on Thursday and Friday.

"All ghats will be cleaned and all debris will be removed within 24 hours of immersion," HMC mayor Rathin Chakraborty promised.

"To reduce river pollution, we have deployed labourers at the ghats who will pull out the bamboo structures as soon as immersion is done. These will be stacked on the ghat and removed later," said Shyamal Mitra, mayoral council member.

Labourers were seen pulling out large structures from the water but by the time they pulled them out, all the clay and straw had been washed away in the river waters. Environmentalist Subhas Dutta said: "A large number of idols remained immersed in water for such a long time. That alone caused pollution."

Immersion in Howrah happens at seven ghats including Shibpur, Ramkrishnapur, Bandhaghat, Chatubabu's ghat, B Garden, Nazirgunge and Pathakghat in Bally. Flowers and other puja accessories were dumped in a vat at the ghat and were not allowed to be carried to the water.