The Chinnar River originates in the Annaimalai Hills below a grassy pass between the hills Kumarikkal Mala (8,275 ft) and Kaladekatti Malai In Idukki District, Kerala state South India. The 18 km long Chinnar river defines the East-West Tamil Nadu/Kerala state boundary along the northern edge of the Chinnar Wildlife Sanctuary and the southern edge of the Indira Gandhi Wildlife Sanctuary. Several adult Crocodiles were reported in the Chinnar river in 1992.