The issue is one of dam height. Supreme Court has allowed raising the water level of this dam in Kerala from 136 ft to 142 ft. Kerala has persistently opposed raising the dam’s water level located in Idukki district on the ground that it would endanger five downstream districts on Kerala side. Also on environmental concerns for the Periyar Tiger Reserve. The SC allowed the TN govt. to carry out the necessary repairs of the dam before the water level is raised to the maximum of 152 ft.