Earth-filling, planting trees: KMDA plans to save Lake’s eroding islands
Times of India | 18 January 2026
Kolkata: The Kolkata Metropolitan Development Authority (KMDA) has planned to rejuvenate and save three large islands, facing erosion over the years, on Rabindra Sarobar, with earth filling and tree plantation.
"According to the data available, the land area has reduced by 8% in the last 20 years. The plan is to do earth filling on the banks of the islands to prevent further erosion," said an official. The islands have also lost many large trees over the years due to natural calamities. "Many trees have been damaged in Cyclone Amphan and the subsequent storms, which occurred over the years. Many trees were also damaged due to bird droppings, which consist of organic compositions that are harmful to trees. Due to these factors, there is hardly any big tree on the islands now," said an official.
Officials said the count of migratory birds visiting the islands—the natural nesting grounds— also reduced a bit due with the number of big trees dropping. "The plan is to plant trees suitable to the character of the soil of the islands. We are taking advice from experts as to what type of trees could be planted on the islands," said an official.
Environmentalists have been raising concerns about the slow but gradual ecological degradation of the Sarobar waterbody over the years. A recent bathymetric survey that was conducted by the authorities showed high sediment accumulation on the lake's bed over the last few years. The report shows an average yearly siltation rate of 8.3 cm since 2022, with the waterbody having an average depth of around 3m to 4m and around 5m in specific sections.
KMDA, on their part, have been taking steps to improve the quality of the Sarobar waterbody. Following recommendations on ways to reduce extra grown submerged aquatic plants and weeds of the lake, the authorities last year released grass carp fish in the water bodies in the Sarobar premises to eat the submerged aquatic plants, which are difficult to remove manually.
KMDA also sprayed quicklime on the Sarobar waterbody to neutralise the toxic elements of the lake, following events of frequent fish deaths. "It was a continuous process to preserve the lake waterbody and its biodiversity," said an official.