Periyar River originates from the Sivagiri hills along the border of Kerala-Tamilnadu. It is the longest river in Kerala. The river runs into the Vembanad Lake and to the Arabian Sea. The length of the river is 244 km. The important dams across this river are Mullaperiyar, Bhuthathankettu, Kundalam,
Cheruthoni, Kulamavu, Irattayar, Lower Periyar, Edamalayar, Chenkulam, Anayirangal and
Ponmudi. The largest hydro electric project, Idukki and the Arch Dam at Idukki are positioned in this river. Other hydro electric projects of this river are Pallivasal, Chenkulam, Panniyar,
Neriyamangalam and Lower Periyar.
The birth place of Shri
Shankaracharya (Kalady), and the renowned Malayatoor church are situated on the banks of the Periyar. Mahashivratri festival is held on the banks of this river in Aluva. Thattekadu Bird Sanctuary is situated on the banks of this river. The well-known wildlife sanctuary and tourist place of Thekkady is located at the side of Mullaperiyar Dam.