Even by conservative estimates, this has saved the city authorities from spending Rs 400 crores on capital expenditure and incurring a recurring maintenance cost on water treatment plants -- want of such huge sums money is a good enough cause to shut down plants in many Third World municipalities (
see illustration)
Additionally, this ecosystem produces more than 10,000 tonnes of fresh and relatively cheaper fish and 147 tonnes (this estimate was done some 20 years back and a new estimate is required) of vegetable daily, just on the outskirts of the city. In this process more than a hundred thousand village folk work out their livelihoods. Indeed if this ecosystem is conserved, the volatile urban edge remains stable and acts as a provider of ecosystem services.
Opportunities and problems The East Calcutta Wetlands has recently been included in the Ramsar list (it contains all internationally significant wetlands). The resource recovery system created and developed by the local people through ages is the largest of its kind in the world apart from being the most people/economy friendly water regime. Kolkata may well stake its claim to be designated as an ecologically subsidised city. But there is a rub: human ability to inflict self injury.
Hooghly's water quality continues to be a problem. The groundwater level in Kolkata has gone down alarmingly and arsenic has been found in the city's aquifer. New urban estates have jeopardised the future of the wetlands. Moreover, the Kulti Gong is rapidly silting up and this can upset the entire drainage system of the city. In short the friendly water regime of Kolkata stands imperiled. The situation, however, can be reasonably remedied if there are sincere efforts.
For ecologists (not just urban) this ecologically subsidised city is an outstanding tutorial ecosystem and can attract students and researchers from all over the world. It has numerous examples of resource cycles that can teach ecology in the most interesting and fundamental manner. For example, snails in pond beds are bad for the fish but are feed for ducks. So, elderly rural women collect these creatures and sell them off to the fisherfolk, who in-turn crush the snails to feed ducks. The birds go back to the ponds and we know that their excreta is food for fish. Traditional knowledge thus makes ecology and economy go hand-in-hand.
Ecologists and environmentalists can draw important lessons in the grammar of living creatively with nature from this. In fact, living creatively with nature should be the founding pedagogy of sustainable development and the East Calcutta Wetlands can be a global hot-spot which can help draw road maps of sustainable development for poorer parts of the world.
Dhrubajyoti Ghosh was formerly chief environment officer, department of environment, government of West Bengal 
