For the first time in the last three decades the state government has come up with a five-year comprehensive plan to protect the East Kolkata Wetlands (EKW) — the 125 square kilometres of natural and human-made diverse habitat which is considered to be the lungs and the kidney of the city.
“The EKW Management Action Plan (2021-26) comprises Institutions and Governance, Water Management and Pollution Conservation of Species and Habitats, and Sustainable Resource. The Plan is a major step forward towards the maintenance of East Kolkata in a healthy condition to enable delivery of their full range of ecosystems of sustaining biological diversity,” state Environment Minister Soumen Mahapatra said.
The Rs 120-crore plan that has already got the necessary approval from the state Finance Department will work on land use and land cover of the wetland; sewage quantity; diversity of biota; reducing species invasion threats to fisheries; reducing livelihood vulnerability; increase of active participation; and a systematic wetlands inventory.
“EKW, a Ramsar site, is capable of naturally treating wastewater. It is not only responsible for preventing the city from massive inundation in case of heavy rain but also ensures that groundwater depletion does not emerge as a major threat to the city. The EKW Management Plan (2021-26) has been conceived after year-long research with the aim to protect the wetlands and at the same time usher in development in the livelihood of the farmers and the fishermen, who are dependent on this unique environment site,” Environment Secretary Vivek Kumar said.
The state government came up with the plan after there was a lot of hue and cry over the encroachment and illegal destruction of the wetlands over the years. The illegal dumping of waste by several urban local bodies resulting in contamination of the water of EKW has been under the scanner of the National Green Tribunal after a petition was filed by environmentalist Subhas Dutta in May 2019. The NGT, in July 2020, had ordered the scientific shifting of legacy waste – also called bio-mining – accumulated in the wetlands for decades.
Located to the eastern fringes of Kolkata City and spanning 12,500 ha, the EKW is a mosaic of landforms including predominantly water dominated areas (used as fish farms) to land-centric usage for agriculture, horticulture and settlements. The existing wetland regime is a remnant of a series of brackish wetlands connected to the freshwater as well as marine environments of the Gangetic Delta and the Bay of Bengal, in an ecological continuum with the Sundarbans. The host is one of the largest sewage fed aquaculture in the world.
Over 260 shallow fish ponds in the EKW receive over 900 MLD pre-settled sewage from the Kolkata Metropolitan Region through a network of locally excavated secondary and tertiary canals, which is used to produce annually 20,000 MT of fish, 50,000 MT of vegetables and irrigate 4700 ha of paddy land. As the nutrient-rich effluent moves through the system, it is progressively cleaned, and nutrients are redirected to the growth of algae or agricultural products grown along the pond edges and agricultural lands.
Algae and other aquatic plants are used to feed up to 17 species of fish cultured in these ponds, which in turn create nitrogen and phosphorus-rich water to irrigate the adjacent rice fields. The traditionally evolved natural water purification waste recovery practice saves Kolkata City nearly Rs 4,680 million annually in terms of the treatment cost of up to 65 per cent of the city’s sewage. These wetlands also lock in over 60 per cent of carbon from wastewater, thus reducing harmful greenhouse gas emissions from the region.
The wetland is inhabited by diverse species. At least 380 major flora including 93 plant families, 10 amphibians, 29 reptiles, 123 birds, 79 fish, 24 crustaceans and 13 mammal species have been recorded in these wetlands. Marsh Mongoose was discovered by the Zoological Survey of India on this wetland.
The traditional waste recovery practice provides subsistence opportunities for a large, economically underprivileged population of 0.15 million living in over 37 mouzas within its boundaries. EKW is also one of the few natural habitats providing recreational avenues for the urban and peri-urban population.