It is a masonry gravity dam located in Kerala's Thekkady, Idukki district, on the Periyar River. It is situated in the Western Ghats highlands, 881 meters above sea level. At the meeting point of the Mullayar and Periyar rivers, the dam is constructed. It is among India's oldest dams. It was finished in 1895, having started construction in 1887. Under Pennycuick's direction, the British Corps of Royal Engineers completed the building. Limestone and "Surkhi," which is a mixture of sugar and calcium oxide and burned brick powder, were used to build the dam. The dam is 53.6 meters (176 feet) high, 365.7 meters (1,200 feet) long, and has a 443 million cubic metre (11.5 billion cubic foot) storage capacity.
It produced an artificial lake and reservoir with a total area of 8.5 square kilometres. The Periyar National Park, a well-known hotspot for biodiversity that is home to many endangered animal and bird species, encircles the dam. The main objective of the dam is to move water from the Periyar River to the Tamil Nadu Vaigai River basin for irrigation and electricity production. Despite being in Kerala, the nearby state of Tamil Nadu is in charge of running and maintaining the dam. The operational rights were transferred to Tamil Nadu in accordance with a 999-year lease arrangement that was negotiated during British control.The safety of the dam has been the subject of a protracted debate between Tamil Nadu and Kerala in recent years. Tamil Nadu has been against any such action, while Kerala has been calling for the dam to be strengthened or decommissioned.
