This sanctuary extends over the Thodupuzha and Udumbanchola taluks of Idukki district, spreading over 77 sq.km. and is about 450-748 m. above sea level.   The Idukki Reservoir formed by three dams - Cheruthoni, Idukki and Kulamanu - extends to 33 sq.km.

This is the world's second and Asia's first arch dam, constructed across the Kuravan and Kurathi hills.  550 ft. high and 650 ft. wide, the dam lies close to the Cheruthoni barrage.  To its west is the Kulamavu Dam.  Idukki Wildlife Sanctuary is located close by.