Boundary

The boundary starts from Thenmala ridge in the north behind  the  Divisional Forest Office and it passes towards east  to  Periyamaruthimalai. In the east it passes between the state boundary of Kerala and Tamil Nadu  through  Periyamaruthimalai  and  Karimalai.  From  Karimalai the boundary runs along  the Southern boundary of the  Division up to 5kms and then  the  boundary between  natural  forests and  plantation till  it  reaches  the Kallada  Reservoir  up  to  the  dam  site. Then the boundary passes along  the  limits  of  the  Reserve  forests  between  Kallada   Dam  and  Thenmala Divisional  forest  office in the west. The interstate boundary length is 21.8kms. 

The boundary of the sanctuary roughly coincides with the watershed boundary of Kallada reservoir in North,  East and South thus making it easy for demarcation and management.  The  outer  boundary  of  the Sanctuary, eastern boundary, is the  interstate  boundary   between  Kerala  and  Tamilnadu,  which is  surveyed and demarcated. 

There are three private enclosures   namely Rosemala,  Kallar estate and  part of  Rockwood  estate  situated  well   inside  the  sanctuary.   These private   enclosures  lie  within  the notified boundary.