Fishers allege Mamallan reservoir plan ignores tidal inundation risks

Fishers and environmental groups in Tamil Nadu have raised serious concerns over the proposed Mamallan reservoir project, arguing that it fails to account for the dangers posed by tidal inundation and storm surges from the Bay of Bengal. At a press conference held in Chennai on Monday, representatives from the Save Nemmeli Marshlands campaign, alongside traditional fishers, environmentalists, and conservationists, demanded that the state government reconsider the project. They pointed to recent studies and assessments that highlight the potential ecological and socio-economic consequences of proceeding with the plan. The protest followed a growing awareness among local communities about the vulnerability of the region to rising sea levels and extreme weather events. Traditional fishers from villages along the Kovalam sub-basin warned that the reservoir's construction could jeopardize their livelihoods. These communities rely heavily on prawn fishing in the backwaters, which are currently protected from seawater intrusion by natural barriers. According to S. Mohana of Periya Nemmeli, the proposed reservoir could disrupt this delicate balance, leading to the loss of their primary means of income. She emphasized that the area is particularly sensitive to tidal fluctuations, and constructing a reservoir so close to the coast could expose them to greater risks during heavy rains and high tides. Local fishermen, including R. Narayanan from Kovalam, shared similar fears. He noted that seawater has regularly entered the marshlands during spring tides and the monsoon season for years. He questioned whether the proposed bunds, dikes intended to control water flow, would effectively prevent seawater from seeping into the reservoir during intense storm surges. The community believes that the current design does not fully address these challenges, leaving them exposed to unpredictable environmental changes. The concerns were supported by experts who reviewed the technical assessments submitted in support of the project’s Coastal Regulation Zone (CRZ) clearance. A study conducted by the Indian Institute of Technology Madras (IIT-M) focused primarily on freshwater inflows from the western catchment, treating the sea merely as an outlet for surplus floodwater. Critics argue that this approach overlooks the complex interactions between the reservoir and the surrounding marine environment. They contend that the proposed outlets, which would release excess water into the Bay of Bengal, might inadvertently allow seawater to infiltrate the reservoir during extreme weather events. Environmental organizations highlighted the ecological significance of the area, describing the wetlands as a critical habitat for diverse wildlife. K.V. Sudhakar, president of the Madras Naturalists' Society, stated that the Kelambakkam-Kovalam-Nemmeli landscape supports a wide range of bird species, with annual counts ranging between 107 and 137. Even during the dry season, the marshlands remain essential for over 135 species, including migratory birds and rare, endangered species listed on the IUCN Red List. Converting this unique ecosystem into a reservoir would not only destroy valuable habitats but also reduce the land’s capacity to act as a natural buffer against floods. The protesters also warned that the conversion of the marshlands into a reservoir would remove approximately 4,375 acres of natural flood storage, potentially exacerbating flooding risks in nearby towns such as Thaiyur, Kelambakkam, Thiruvidanthai, Padur, Pattipulam, Saluvankuppam, and Mamallapuram. These areas are already prone to seasonal flooding, and the loss of natural absorption zones could lead to more frequent and severe inundations. As the debate continues, the state government faces mounting pressure to reassess the project’s feasibility and environmental impact. With climate change intensifying the frequency and severity of coastal storms, the need for sustainable infrastructure planning has never been more urgent. The outcome of this controversy will likely shape future policies on coastal development in Tamil Nadu.