The Supreme Court has upheld the validity of the Parambikulam Aiyar Project (regulation of water-supply) Act, 1993, which seeks to supply water on a rotational basis once in two years to each zone in four specified zones of Coimbatore district.The water would be used to irrigate about 3,77,152 acres covered under the project as against the earlier supply of water once in 18 months on rotational basis in three specified zones to irrigate 2,03,299 acres.