East Kolkata Wetlands as a Mosaic

Sluices, pumping stations, lock gates, and mortar sewers constitute an intricate network arrangement with a colonial footprint. This network required that multiple entities play equally important roles in managing the various processes and functions of the wetland system. An important step in the wastewater distribution system is the Bantala Lock Gate—a set of 10 sluice gates that are manually operated to distribute sewage using gravity to the fishponds through interconnected carrier channels.

The bheris or sewage-fed ponds pre-settled sewage from the dry weather flow canal through an intricate series of locally excavated secondary and tertiary channels. The numerous inlets that connect the main canal to the fishponds and cultivable plots, bring with them histories and stories of the earliest leaseholders who were encouraged to practice sewage-fed aquaculture and farming by the Calcutta Corporation during the late 1870s. Like smaller branches growing from the bigger ones, these crucial water trails circulate wastewater to the fishponds. Wastewater management processes ensure the time and amount of wastewater release as well as dredging of the inlets.

Wastewater and municipal solid waste are co-recycled in the EKW through traditional mechanisms and recovery practices followed by fisherfolk and farmers. There are three types of waste stabilization ponds (WSPs) currently functional in the EKW—anaerobic ponds, facultative ponds, and maturation ponds.

In the WSPs, natural sewage treatment involves five distinct phases: pond preparation, primary fertilization, fish stocking, secondary fertilization, and fish harvesting.

Each phase begins with a meticulous and collaborative management of wastewater flow and distribution which then create the optimal conditions for pond preparation and aquaculture practices. In conjunction with coordinated technological operations, fisherfolk traditional knowledge, skillsets and wisdom have co-established the East Kolkata Wetlands.

The fish cultivated in the wastewater not only help plankton thrive in the ponds, but also convert available nutrients into a consumable form. Solids removed are composted and used to fertilize the rice and vegetable fields of the neighborhood. This ecosystem-based livelihood practice enables the fishers and farmers to sell excess produce in the city’s markets. EKW’s role in the city’s social and ecological system is evident from the material flows between the two. The wetlands receive wastewater as a resource from the city which, in return, obtain fish from the wetlands, ensuring urban metabolism and sustainability. 

This resource recovery system is challenged by innumerable stressors—from the wastewater channels’ siltation to growing urbanization that triggers real estate encroachments and conversion of wetlands. Unauthorized constructions, commercial ventures, and creation of new lands for the city by filling up waterbodies are commonplace. Social and economic insecurities shaped by exclusionary governance mechanisms and political equations are filling up this socioecological space with contestations and negotiations. It is imperative to develop a shared dialog among local stakeholders, academicians, civil society groups, grassroot activists, government agencies, and policy makers to ensure collaborative action to address the current sustainability challenges of the EKW.