<b>Subir Roy:</b> Kolkata wetlands an endangered species

The east Kolkata wetlands, the biggest ecological asset of the city and a Ramsar Site, are on their deathbed. A political heavyweight has been appointed as de facto undertaker to do the last rites, so to speak. 

A Ramsar Site is a wetland (shallow waters) which is designated to be of international importance under the Convention on Wetlands, an intergovernmental environmental treaty established nearly 50 years ago (1971) by Unesco. (It came into force in 1975 and takes its name from Ramsar, the Iranian city where the convention was adopted.) A city should consider itself lucky to have such a natural asset next to itself. 

The east Kolkata wetlands are a fascinating natural resource to which tremendous value has been added by traditional knowledge. The wetlands have been historically  created by a natural shift of the Bidyadhari, a tributary of the Ganga. As the land on which Kolkata is built slopes to the east, the British who built the city created canals to take out the city’s waste water, which ends up in the wetlands. 

What happens to this waste water is where traditional knowledge comes in. For around a century, raw sewage has been first fed into settling ponds where biodegradation of organic components takes place. Then the nutrient-rich sewage is transferred into a fish pond where, in sunlight, there is formation of algal bloom and reduction in biochemical oxygen demand (BOD), indicating improvement in the organic quality of the water. Fish is grown in this pond and the used water is transferred to fields to irrigate crop. 

The wetlands are not all wet. In the currently designated 12,500 hectares of wetlands, water bodies account for almost half (46 per cent), agricultural land takes up 39 per cent, garbage landfills nearly 5 per cent and urban and rural settlements over 10 per cent. The wetlands grow 10,500 tonnes of fish per year and 150 tonnes of vegetables per day, providing livelihood for over 50,000 people. The solid waste brought to the landfills is composted in pits in the usual manner and used for growing paddy and vegetables. Around 680 million litres of sewage is “treated” at the wetlands, not just saving Rs 500 crore annually in treatment costs, but also helping grow fish and vegetables. 

The “undertaker” mentioned above is Sovan Chatterjee (ironically the state’s environment minister and the city’s mayor to boot) who was last month made chairman of the East Kolkata Wetlands Management Authority, replacing the state’s chief secretary. The state government obviously has designs on the wetlands as Chatterjee wants “proper utilisation” of the land currently lying barren there, say news reports. Bare land along the EM Bypass, a key arterial road and growth corridor of the city, should be properly utilised “without losing crucial balance in ecology”. He has further assured that he “will not allow anyone to fill up a single pond or water body”. 

What will he do with his new responsibility? Hundreds of illegal construction has taken place for which ownership title could not be recorded and property taxes collected. Other than raising taxes what else will he do? Build a park that will combine Singapore’s Jurong Bird Park and Bangkok’s Safari World. 

The reality is that the wetlands are slowly and steadily disappearing and if past trend is anything to go by, there will not be much left of them in time. How bad is the vanishing act? According to one study, satellite imagery indicates that in one mouza (administrative area), Bhagabanpur, a part of the wetlands, water bodies have shrunk from 77 per cent to 14 per cent of the area since 2002. This is corroborated by census data which say that during the 2001-11 decade, there was a fourfold rise in the number of houses and population density in the area. Another study says that during 1996-2016, the number of large bheris (water bodies devoted to growing fish) in the area went down from 47 to 10. There is no dispute that encroachments in the wetlands began during the Left Front rule but have been picking up speed over time. 

Land sharks with links to the local politically powerful and administration explain the disappearing wetlands but that is not the sole danger. The nature of the liquid waste coming to the wetlands from the city is changing. The presence of non-biodegradable chemicals is increasing as income and lifestyle in the city change. The chemicals to watch out for are lead and mercury used for the manufacture of batteries, paint and glass. Hence, measuring the presence of these in the water and the fish regularly is vital. 

This will ring a timely warning bell but eventually the kind of waste water that has been good for fish cultivation for most of the last century will not be there. So the city will have to forget about relishing the fish and vegetables that come out of the wetlands. 

But even after the waste water is no longer what it used to be, one key use of the wetlands will remain — be a home for migratory birds. For this you don’t need to build amusement parks using a lot of bricks and mortar but simply let the wetlands be what they are, the less untouched by human hands the better.  

subirkroy@gmail.com