Spanning 1,400 hectares, Anawilundawa is one of the 6 RAMSAR wetlands in Sri Lanka. Comprised of an ancient system of human-made cascading tanks and reservoirs and fed by flood waters of the Deduru Oya, Anawilundawa sustains rice paddy fields, wildlife, and natural vegetation. The tanks store water for irrigation, and also play a major role in flood control, aquifer recharge, retention of pollutants and sediments, and nutrient export.