The Ashtamudi, Sasthamkotta and Vembanad kol wetlands (2195 km. sq.) of Kerala have been designated as Ramsar Sites by the Ramsar Convention, giving them international importance. Vembanad Kol Wetland System, the largest brackish tropical wetland ecosystem on the south west coast of India, fed by 10 rivers and typical of large estuarine systems on the western coast is renowned for the clams and supporting the third largest migratory water fowl population in India during the winter months. Vembanad Kol spreads across Alappuzha, Kottayam, Ernakulam, Thrissur and Malappuram districts. The Ashtamudi Lake, an extensive estuarine system, the second largest in Kerala, is of extraordinary importance for its hydrological functions, its biodiversity, and its support for fish. Sasthamkotta is a fresh water wetland. While the other two are saline wetlands.