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Hilsa worries on Hooghly

While the salmon is coming back to the Thames, the hilsa is vanishing from the Ganga — and this fishy business sums up the tale of the two iconic rivers.

“Calcutta can learn a thing or two from London on conserving its own river,” environment activist Subhas Dutta said recently during a cruise on the Hooghly (as the Ganga is known in these parts).

The Thames and the Ganga have much in common. Both have tidal and non-tidal sections, both are critical to the existence of the cities they flow through and both have important ports to sustain. Yet they are vastly different.

While today the Thames is considered one of the cleanest rivers in the world that flows through a major city, according to a report by the high court-appointed expert committee, the Calcutta stretch of the Ganga is the most polluted in all of West Bengal.

Both rivers have regular dredging to ensure navigation, but the process is very different. Every year Calcutta and Haldia ports spend about Rs 400cr to dredge about 20m cubic feet of silt but never consider the environmental aspects, said Dutta.

In contrast, London and Liverpool ports conduct thorough survey on a series of environmental aspects before any dredging. The criteria considered in London include morphology of animals, quality of water, quality of dredged materials, noise level of dredging operation, status of toxic chemicals and metals in the riverbank and effects on birds.

Dutta also pointed out how the Thames had been turned around from being “biologically dead” in 1950s to its present condition.

But for the Hooghly today, it’s not just the hilsa that disappearing. “Not only hilsa, even dolphins and various bird species can hardly be located now,” rued Lt Col (retired) S.R. Banerjee. The Thames now has hundreds of fish and other aquatic species.

That is because no untreated effluent is allowed to enter the Thames. But the Ganga has almost turned into a toxic sludge flow with untreated effluent from numerous industries, cities and various human activities added to the river at various points — 324 points to be precise, according to a study carried out by the National Environmental Engineering Research Institute.

Biswajit Mukherjee, a retired chief law officer of the state pollution control board, said that numerous brick fields, using the river bank as an open-air toilet for millions, stationary vessels seeping toxic waste into the river, dumping of solid waste at both banks, illegal sand mining and encroachments further affect the health of the Hooghly.

R.P.S. Kahlon, the chairman of the Calcutta Port Trust, said he was aware of the condition of the river and would take up environment improvement programmes for the river soon.