A lease deed was executed in 1886 between the Maharaja of Travancore and the Secretary of the State for India, for irrigation works by the Madras Presidency for diverting all waters of Periyar River of Kerala flowing into the land bounded by a contour line of 155 ft above the deepest point of the bed of the Periyar river to Vaigai basin for a period of 999 years. Two supplemental agreements were executed in 1970 by the successor Governments of Kerala and Tamil Nadu. As per the first supplement agreement, the lease rent was enhanced from Rs.5 per acre to Rs.30 per acre with a provision to revise the same in every 30 years. The second one permitted Tamil Nadu to generate electricity using the waters of Mullaperiyar.