The Periyar River originates in Kerala’s Western Ghats near the Tamil Nadu border and then flows in the northerly direction to the Periyar National Park. The Periyar Lake was created by the British in 1895 with the building of the Mullaperiyar and forms a major watershed for the sanctuary and for both states.  The lake forms the nucleus of the reserve,  providing a great habitat for water birds such as darters, grey herons, egrets, cormorants and kingfishers.