The Periyar valley Irrigation project in Ernakulam district envisages the utilization of the tail race discharge from the completed Hydel scheme in the Muthirapuzha tributary of river Periyar together with the controlled release from Ennackal dam constructed by Kerala State Electricity Board under Hydel scheme across the Idamalayar tributary and the dependable run off from the uncontrolled catchment of Periyar river, for irrigating an area of 32800 hectares of land lying on the left bank of Periyar river through a network of canal system and controlling devices.