Breathing life into Vembanad lake Premium

Rejuvenating Vembanad lake is critical for Kerala, but it is easier said than done

Vembanad, the longest lake in India and the largest in Kerala, is gasping for breath. The 96.5 km-long water body spans the districts of Alappuzha, Kottayam, and Ernakulam and forms part of the Vembanad-Kol wetland system, a Ramsar site. Six major rivers drain into the lake, which accounts for around 30% of the State’s total surface water resource.

Over the past century, the lake has shrunk significantly due to human-induced interventions, land reclamation, and natural sedimentation, according to experts. Though vital to the region’s ecology and agriculture, it faces severe threats from pollution, eutrophication, unsustainable agricultural practices, and invasive weed proliferation.

A few years ago, a study by the Kerala University of Fisheries and Ocean Studies revealed alarming levels of plastic waste, silt, and other sediments in the lake. According to a recent expert committee report prepared as part of the Vembanad Lake Rejuvenation Project, an ambitious joint effort of the Alappuzha district administration and the Local Self Government Department, the lake’s surface area has shrunk mainly due to land encroachment. Citing previous studies, the report notes that the surface area of the lake diminished by 27% between 1917 and 1990. The drastic reduction in not only area, but also depth, has significantly reduced the lake’s floodwater retention capacity and impaired its critical ecosystem services, including water purification, biodiversity support, and sediment transport. The unchecked proliferation of water hyacinths has further worsened the situation, contributing to dangerously high levels of chemical oxygen demand and biological oxygen demand. As a result, the fish catch has declined by about 66% over the last three decades.

The efforts to rejuvenate the lake are being spearheaded by Alappuzha District Collector Alex Varghese. The initiative draws “inspiration from the Namami Gange Programme”. It gained momentum on October 28, 2024 when a workshop was held focusing on addressing the challenges of restoring the water body. Eight subcommittees — agriculture, fisheries, water resources, tourism, biodiversity, environment and sanitation, disaster management and climate change, and revenue — were constituted. A ₹188.25 crore comprehensive five-year plan was formulated and recently submitted to Chief Minister Pinarayi Vijayan. The estimate may be revised based on the detailed study on water resources and irrigation projects being conducted by the Centre for Water Resources Development and Management.

The short-term goals include the removal of plastic waste, construction of bio-shields to protect farmlands, fish ranching, weed eradication, and the construction of 31 bio bunds, each 1 km long in 31 grama panchayats. The long-term targets include dredging the lake bed to increase its water-holding capacity, promoting organic farming to prevent pollution from pesticides and chemicals, conserving the flora and fauna, establishing sewage and faecal sludge treatment plants in flood-prone Kuttanad, manufacturing value-added products from water hyacinth, and boosting tourism and fish yield.

While the report is under the State government’s consideration, 28.72 tonnes of plastic waste and a greater quantity of water hyacinth were removed from the lake in recent mega cleaning drives conducted under the aegis of the Alappuzha district administration.

Rejuvenating the lake is critical for enhancing the region’s resilience to climate change impacts such as erratic rainfall, sea-level rise, and intensified flooding events. However, it is easier said than done. For instance, houseboats are among the top sources of pollution in the lake. While the report calls for enacting strict laws against unauthorised vessels, previous efforts to rein in illegal houseboat operations have been largely ineffective. Another significant hurdle is land encroachment. The expert committee report notes that reclaiming encroached areas “necessitates strong political support and decisive action.” Since Kuttanad is part of the Vembanad wetland ecosystem, the lake’s restoration should be linked to the revival of the entire Kuttanad region.